Window 7 users: Hit "log In" to see if your computer is secure and can view the HTTPS:// secure connection, SSL. If not, please call in your O-Ring order. 

8am-4pm Pacific Mon-Fri | 208-413-6377

-300 Series 3/16" CS




Image Model+ Item Name Stock Price Quantity Discounts
ST321 Single Turn Split Teflon Backup Ring ST321

ST321 Single Turn Split Teflon Backup Ring

AS568-321 (0.183" W X 1.200"ID X 0.076"HT) Teflon PTFE Back-up Rings are designed to prevent extrusion in rubber O-ring sealing...
0
$6.98

Add:

Quantity Discounts
1-4$6.98
5-28$5.24
29+$3.49
ST324 Single Turn Split Teflon Backup Ring ST324

ST324 Single Turn Split Teflon Backup Ring

AS568-324 Teflon PTFE Back-up Rings are designed to prevent extrusion in rubber O-ring sealing systems. The amount of this extrusion is affected by...
30
$2.49

Add:

Quantity Discounts
1-66$2.49
67-399$1.87
400+$1.25
ST325 Single Turn Split Teflon Backup Ring ST325

ST325 Single Turn Split Teflon Backup Ring

AS568-325 (0.183" W X 1.513"ID X 0.076"HT) Teflon PTFE Back-up Rings are designed to prevent extrusion in rubber O-ring sealing...
95
$1.22

Add:

Quantity Discounts
1-27$1.22
28-163$0.92
164+$0.61
ST326 Single Turn Split Teflon Backup Ring ST326

ST326 Single Turn Split Teflon Backup Ring

AS568-326 (0.183" W X 1.638"ID X 0.076"HT) Teflon PTFE Back-up Rings are designed to prevent extrusion in rubber O-ring sealing...
108
$1.25

Add:

Quantity Discounts
1-26$1.25
27-158$0.94
159+$0.63
ST327 Single Turn Split Teflon Backup Ring ST327

ST327 Single Turn Split Teflon Backup Ring

AS568-327 (0.183" W X 1.763"ID X 0.076"HT) Teflon PTFE Back-up Rings are designed to prevent extrusion in rubber O-ring sealing...
7
$1.35

Add:

Quantity Discounts
1-24$1.35
25-147$1.01
148+$0.68
ST328 Single Turn Split Teflon Backup Ring ST328

ST328 Single Turn Split Teflon Backup Ring

AS568-328 (0.183" W X 1.888"ID X 0.076"HT) Teflon PTFE Back-up Rings are designed to prevent extrusion in rubber O-ring sealing...
43
$1.37

Add:

Quantity Discounts
1-24$1.37
25-144$1.03
145+$0.69
ST329 Single Turn Split Teflon Backup Ring ST329

ST329 Single Turn Split Teflon Backup Ring

AS568-329 (0.183" W X 2.013"ID X 0.076"HT) Teflon PTFE Back-up Rings are designed to prevent extrusion in rubber O-ring sealing...
0
$1.48

Add:

Quantity Discounts
1-22$1.48
23-135$1.11
136+$0.74
ST330 Single Turn Split Teflon Backup Ring ST330

ST330 Single Turn Split Teflon Backup Ring

AS568-330 (0.183" W X 2.138"ID X 0.076"HT) Teflon PTFE Back-up Rings are designed to prevent extrusion in rubber O-ring sealing...
87
$1.62

Add:

Quantity Discounts
1-20$1.62
21-123$1.22
124+$0.81
ST331 Single Turn Split Teflon Backup Ring ST331

ST331 Single Turn Split Teflon Backup Ring

AS568-331 (0.183" W X 2.268"ID X 0.076"HT) Teflon PTFE Back-up Rings are designed to prevent extrusion in rubber O-ring sealing...
0
$1.63

Add:

Quantity Discounts
1-20$1.63
21-121$1.22
122+$0.82
ST332 Single Turn Split Teflon Backup Ring ST332

ST332 Single Turn Split Teflon Backup Ring

AS568-332 (0.183" W X 2.393"ID X 0.076"HT) Teflon PTFE Back-up Rings are designed to prevent extrusion in rubber O-ring sealing...
44
$1.82

Add:

Quantity Discounts
1-18$1.82
19-109$1.37
110+$0.91
ST333 Single Turn Split Teflon Backup Ring ST333

ST333 Single Turn Split Teflon Backup Ring

AS568-333 (0.183" W X 2.518"ID X 0.076"HT) Teflon PTFE Back-up Rings are designed to prevent extrusion in rubber O-ring sealing...
48
$1.84

Add:

Quantity Discounts
1-18$1.84
19-108$1.38
109+$0.92
ST334 Single Turn Split Teflon Backup Ring ST334

ST334 Single Turn Split Teflon Backup Ring

AS568-334 (0.183" W X 2.643"ID X 0.076"HT) Teflon PTFE Back-up Rings are designed to prevent extrusion in rubber O-ring sealing...
31
$1.97

Add:

Quantity Discounts
1-16$1.97
17-101$1.48
102+$0.99
ST335 Single Turn Split Teflon Backup Ring ST335

ST335 Single Turn Split Teflon Backup Ring

AS568-335 (0.183" W X 2.768"ID X 0.076"HT) Teflon PTFE Back-up Rings are designed to prevent extrusion in rubber O-ring sealing...
0
$2.20

Add:

Quantity Discounts
1-15$2.20
16-90$1.65
91+$1.10
ST336 Single Turn Split Teflon Backup Ring ST336

ST336 Single Turn Split Teflon Backup Ring

AS568-336 (0.183" W X 2.893"ID X 0.076"HT) Teflon PTFE Back-up Rings are designed to prevent extrusion in rubber O-ring sealing...
-2
$2.24

Add:

Quantity Discounts
1-14$2.24
15-89$1.68
90+$1.12
ST337 Single Turn Split Teflon Backup Ring ST337

ST337 Single Turn Split Teflon Backup Ring

AS568-337 (0.183" W X 3.018"ID X 0.076"HT) Teflon PTFE Back-up Rings are designed to prevent extrusion in rubber O-ring sealing...
0
$2.32

Add:

Quantity Discounts
1-14$2.32
15-86$1.74
87+$1.16
ST338 Single Turn Split Teflon Backup Ring ST338

ST338 Single Turn Split Teflon Backup Ring

AS568-338 (0.183" W X 3.143"ID X 0.076"HT) Teflon PTFE Back-up Rings are designed to prevent extrusion in rubber O-ring sealing...
19
$2.36

Add:

Quantity Discounts
1-14$2.36
15-84$1.77
85+$1.18
ST339 Single Turn Split Teflon Backup Ring ST339

ST339 Single Turn Split Teflon Backup Ring

AS568-339 (0.183" W X 3.273"ID X 0.076"HT) Teflon PTFE Back-up Rings are designed to prevent extrusion in rubber O-ring sealing...
0
$2.40

Add:

Quantity Discounts
1-13$2.40
14-83$1.80
84+$1.20
ST340 Single Turn Split Teflon Backup Ring ST340

ST340 Single Turn Split Teflon Backup Ring

AS568-340 (0.183" W X 3.398"ID X 0.076"HT) Teflon PTFE Back-up Rings are designed to prevent extrusion in rubber O-ring sealing...
0
$2.47

Add:

Quantity Discounts
1-13$2.47
14-80$1.85
81+$1.24
ST341 Single Turn Split Teflon Backup Ring ST341

ST341 Single Turn Split Teflon Backup Ring

AS568-341 (0.183" W X 3.523"ID X 0.076"HT) Teflon PTFE Back-up Rings are designed to prevent extrusion in rubber O-ring sealing...
0
$2.60

Add:

Quantity Discounts
1-12$2.60
13-76$1.95
77+$1.30
ST342 Single Turn Split Teflon Backup Ring ST342

ST342 Single Turn Split Teflon Backup Ring

AS568-342 (0.183" W X 3.648"ID X 0.076"HT) Teflon PTFE Back-up Rings are designed to prevent extrusion in rubber O-ring sealing...
10
$2.68

Add:

Quantity Discounts
1-12$2.68
13-74$2.01
75+$1.34


What are the most common O-ring compounds?

We stock O-Rings in over 20 different compounds and durometers the following six are the standard rubber materials in a range of durometers (Shore A) hardness to satisfy practically any service condition:

Buna-N O-Rings / Nitrile O-Rings / NBR: Nitrile (Buna-N) is the most widely used elastomer due to its excellent resistance to petroleum products, operating temperature range (-40°F to +257°F) and one of the best performance-to-cost values. It's an ideal material for aerospace, automotive, propane and natural gas applications. Special Hydrogenated Nitrile (HNBR) compounds can improve resistance to direct ozone, sunlight, and weather exposure while increasing temperature range to +300°F.
AS-568 Buna-N O-Rings | Metric Buna-N O-Rings

Viton® O-Rings / FKM: Fluorocarbon (Viton®) exhibits exceptional resistance to chemicals, oils, temperature extremes (-13°F to +446°F), low compression set, low gas permeability and excellent aging characteristics. Applications include: aircraft engines, automotive fuel handling systems, and chemical processing industries. FKM is also suitable for high vacuum applications. It is not recommended for exposure to ketones, alkalis, and Skydrol® fluids. Custom compounds are available with improved chemical and low temperature resistance.
AS-568 Viton® O-Rings | Metric Viton® O-Rings

Ethylene-Propylene / EPDM O-Rings: EPDM has outstanding resistance to heat, water and steam, alkali, mild acidic and oxygenated solvents, ozone, and sunlight (-40ºF to +275ºF); but it is not recommended for gasoline, petroleum oil and grease, and hydrocarbon environments. This popular rubber compound is usually the first choice for low torque drive belt applications.
AS-568 EPDM O-Rings | Metric EPDM O-Rings

Silicone O-Rings / VMQ: In the Silicone family, you will find compounds which are superior as static seals in extreme temperature conditions. Standard compounds handle operating temperatures -85º to +400ºF. Silicone compounds are popular in food and medical applications because they are very clean and do not impart odor or taste. Special Phenyl silicones can be used down to -148°F.
AS-568 Silicone O-Rings | Metric Silicone O-Rings

Neoprene® O-Rings / CR: Neoprene (-40º to +250ºF) is reasonably priced and features good resistance to petroleum oils, ozone, sunlight and oxygen aging, relatively low compression set, good resilience and outstanding physical toughness. It is the preferred sealing material for the refrigeration industry because of its resistance to ammonia and Freon®.
AS-568 Neoprene® O-Rings