OSK™ O-Ring Kit – 200 Piece | 12 Sizes | Buna-N Nitrile | 70 Duro – Square Rings

OSK™ K200X12SN70 is a 200 piece Buna-N 70 Duro square O-Ring assortment kit with 12 popular AS568-style square ring sizes. This kit is made for maintenance shops, service trucks, repair benches, and equipment owners who need common square cut sealing rings ready for fast repairs. It helps reduce downtime, avoid extra supply runs, and keep the right replacement square O-Rings organized and easy to find.

Benefits

This OSK™ square O-Ring kit helps keep repairs moving when a machine, tool, fitting, or assembly needs a common square cut seal.

The customer benefit is simple:

• Keeps 12 popular square O-Ring sizes on hand
• Helps reduce downtime during repair work
• Saves trips to the parts counter
• Helps technicians find the right size faster
• Gives shops a useful mix of small and medium square ring sizes
• Supports faster repair decisions when the original seal is worn, cut, or missing
• Helps prevent delays caused by not having a common replacement seal ready

This kit is more than a box of rubber parts. It gives your shop a ready-to-use sealing assortment so repairs can be completed with less guessing and less frustration.

Correct Size Coverage

This 200 piece square O-Ring assortment includes 12 popular AS568-style sizes. Inch dimensions are listed first, followed by metric dimensions.

Metric size reference:

SAE, Metric, or Specialty Kit Type

This is an SAE AS568-style square O-Ring assortment kit.

It is a specialty square ring kit, not a standard round O-Ring kit. Square O-Rings, also called square cut washer rings in some applications, have a square cross section instead of a round cross section. This makes the kit useful when the repair calls for a square profile seal.

Use this kit when the original seal size and shape match the square O-Rings listed above.

Material Compatibility

These square O-Rings are made from Buna-N Nitrile, also known as NBR.

Buna-N is a common general-purpose rubber used for many shop, maintenance, and equipment repairs. Standard NBR grades are typically used with:

• Mineral oil-based lubricants
• Greases
• Many hydraulic fluids
• Aliphatic hydrocarbons
• Silicone oils and greases
• Water applications up to about 80°C

Operating temperature range:

• -40°F to 212°F

Buna-N is not the right material for every fluid. For critical applications, confirm the fluid, temperature, pressure, and environment before using this kit.

Durometer and Seal Performance

This kit uses 70 Duro Buna-N square O-Rings.

70 Duro means the rubber has a common general-purpose hardness. It is firm enough for many sealing jobs while still allowing the seal to compress during installation.

Durometer matters because it affects:

• How the seal compresses
• How well it fills the sealing space
• How it handles pressure
• How long it may last in service
• How easy it is to install

For most general repair work, 70 Duro Buna-N is a practical choice. For higher pressure hydraulic fittings or applications where extrusion resistance is more important, a harder material such as 90 Duro may be required.

Best Uses

This square O-Ring kit is a good fit for:

• Maintenance shops
• Service trucks
• Manufacturing maintenance areas
• Farm and equipment repair
• General shop repair
• Automotive repair when the size and material match
• Hydraulic and pneumatic repair when Buna-N 70 is compatible
• Small equipment repair
• OEM maintenance areas
• Replacement of matching square cut seals

This kit is not ideal for unknown chemicals, critical aerospace, medical, food contact, or highly specified applications unless the required material, hardness, certification, and traceability are confirmed before use.

Quality and Reliability

The OSK™ K200X12N70 kit is built as a professional repair and maintenance assortment. The value is in having known sizes, known material, known hardness, and useful quantities ready when work needs to be done.

A better O-Ring kit helps reduce:

• Wrong-size repairs
• Wasted time
• Extra supply trips
• Delayed jobs
• Repeat failures caused by poor seal selection

The O-Ring Store LLC is ISO9001:2015 certified, and this kit is assembled to support fast, accurate, and practical seal replacement.

Organized Storage Case

This kit is organized to help the customer find the correct square O-Ring size faster during a repair.

An organized assortment helps technicians:

• Compare the old seal to the listed size
• Keep common sizes separated
• Reduce time spent searching for loose parts
• Store the kit on a shop bench, maintenance cart, or service truck
• See when a compartment is running low

Fast size selection is a real customer benefit. It keeps the repair moving.

Piece Count and Refill Value

This kit includes 200 total square O-Rings in 12 useful sizes.

The piece count is helpful, but the real value is the size mix. The kit includes higher quantities of the smaller, more commonly used sizes and practical refill counts for larger sizes.

Customers can reorder replacement O-Rings from The O-Ring Store LLC when compartments run low. That means the customer does not need to replace the whole kit just because a few common sizes were used first.

Price and Buying Value

This kit is a smart repair purchase because it helps prevent downtime and keeps common square O-Rings ready for use.

The value is not just the price of the rubber. The value is:

• Faster repairs
• Fewer interruptions
• Less time searching for parts
• Better shop organization
• Fewer emergency supply runs
• More completed jobs with less frustration

For maintenance teams, service trucks, and repair shops, a stocked square O-Ring assortment can pay for itself quickly when it helps avoid one delayed repair.

Before You Buy

Before ordering, confirm the seal size and material needed for your repair.

Check these items first:

• Match the O-Ring size to the gland or original square O-Ring
• Confirm ID, OD, and CS before use
• Match Buna-N to the fluid, temperature, pressure, and environment
• Do not assume all rubber materials work in every fluid
• For critical applications, confirm material, hardness, certification, and traceability requirements before use

If the old seal is swollen, flattened, cut, or stretched, measure the gland when possible. A damaged seal may not show the original size clearly.

Why Buy From The O-Ring Store LLC

The O-Ring Store LLC is an ISO9001:2015 certified O-Ring and seal distributor. We make getting O-Rings easy.

Customers get more than a kit. They get clear sizing, practical product information, refill options, and support from a team that works with O-Rings and seals every day.

The benefit to the customer is speed, accuracy, service, and the ability to keep the kit working over time. When common sizes run low, replacement O-Rings can be ordered without starting over with a new kit.

FAQ

What is this square O-Ring kit used for?
It is used for repair and maintenance jobs that require square cut Buna-N O-Rings in common AS568-style sizes.

Is this kit SAE or metric?
This is an SAE AS568-style square O-Ring kit. Metric dimensions are also listed to help confirm size.

What material are the O-Rings?
The O-Rings are Buna-N Nitrile, also called NBR, in 70 Duro hardness.

Can I use this kit with hydraulic oil?
Buna-N is commonly used with many mineral oil-based hydraulic fluids. Always confirm fluid compatibility for your application.

Can I refill this kit?
Yes. Replacement O-Rings can be ordered from The O-Ring Store LLC when compartments run low.

What is the difference between square O-Rings and standard O-Rings?
Square O-Rings have a square cross section. Standard O-Rings have a round cross section. Use the style that matches the original seal or gland design.