O-Rings
Standard AS568 O-rings by dash number, from tiny 001 rings up through the larger 300 and 400 series sizes.
Browse O-RingsO-rings and seals
The right seal, the first time.
A leaking cylinder, pump or fitting usually comes down to one small ring. Retmay stocks O-rings across the standard AS568 dash sizes, plus O-ring boss seals for straight-thread ports, so the right ring is on the shelf when the old one fails.
Why it matters
Small part, expensive leak.
An O-ring costs pennies, but the wrong one costs a second teardown. A ring that is a size too small stretches and thins; one that is too large rolls or pinches in the groove. Either way the leak comes back, usually after the machine is back in service.
Dash numbers take the guesswork out. Each AS568 number stands for a fixed inside diameter and cross-section, so a 2-112 is the same size from any maker. If the old ring is too damaged to read, measure its inside diameter and cross-section and match those to the chart.
Shops that see regular hydraulic or air work keep a run of common dash sizes on hand. A compartment box with one size per compartment, or one of our O-ring kits, keeps a repair from waiting on an order.
Shop by type
Find the right type.
Each type links to its full list with photos, list prices and stock.
O-Ring Boss Seals
O-rings sized for SAE straight-thread O-ring boss ports, the seal under ORB hydraulic fittings.
Search O-Ring Boss SealsChoosing
Match it to the job.
Read the old ring
Find the dash size
If the part number or dash size is known, order by it. Otherwise measure the inside diameter and cross-section of the old ring, or of the groove it sits in.
Check the job
Match the seal to the port
Use boss seals under straight-thread ORB fittings and standard rings in grooves, caps and valves. Ask us when a job calls for a special compound.
Keep a spare run
Stock the sizes you use
A kit or a labeled compartment box of the sizes your equipment uses turns a parts run into a five-minute fix.
Getting started
Ordering in three steps.
- Note the dash size, or measure the inside diameter and cross-section of the old ring.
- Confirm whether the seal sits in a groove or under an O-ring boss fitting.
- Order the ring by Retmay item number, or ask us to build a kit of the sizes you replace most.
Related
Need the fittings too? O-ring boss fittings are in Fittings, and O-ring kits are in Assortments. Store a full run of sizes in a Durham compartment box.
Questions
O-Rings FAQs
What does the dash number on an O-ring mean?
It is the AS568 standard size. Each dash number stands for a set inside diameter and cross-section, so the same number fits the same groove regardless of brand.
How do I size an O-ring with no part number?
Measure the inside diameter and the cross-section (thickness) of the old ring, or measure the groove. Send us the numbers and we will match the dash size.
What is an O-ring boss seal?
The O-ring that seals an SAE straight-thread (ORB) fitting against its port. It is sized to the thread, not to a groove.
Can you put together a kit of the sizes we use?
Yes. Send the dash sizes your equipment uses and we can quote a kit or a stocked compartment box.