Buna-N Back-Ups 90 Durometer Rings

• O-Ring Sizing Chart (PDF)
• O-Ring Material Guide (PDF)

Master Item #	Actual Size I.D. (in)	Actual Size I.D. (mm)	Actual Size I.D. Tolerance (in)	Actual Size I.D. Tolerance (mm)	Actual Size W. (in)	Actual Size W. (mm)	Actual Size W. Tolerance (in)	Actual Size W. Tolerance (mm)
AS 568A-277	11.484	291.69	±.065	±1.65	0.139	3.53	±.004	±0.10
AS 568A-278	11.984	304.39	±.065	±1.65	0.139	3.53	±.004	±0.10
AS 568A-279	12.984	329.79	±.065	±1.65	0.139	3.53	±.004	±0.10
AS 568A-280	13.984	355.19	±.065	±1.65	0.139	3.53	±.004	±0.10
AS 568A-281	14.984	380.59	±.065	±1.65	0.139	3.53	±.004	±0.10
AS 568A-282	15.955	405.26	±.075	±1.91	0.139	3.53	±.004	±0.10
AS 568A-283	16.955	430.66	±.080	±2.03	0.139	3.53	±.004	±0.10
AS 568A-284	17.955	456.06	±.085	±2.16	0.139	3.53	±.004	±0.10
AS 568A-309	0.412	10.46	±.005	±0.13	0.21	5.33	±.005	±0.13
AS 568A-310	0.475	12.07	±.005	±0.13	0.21	5.33	±.005	±0.13
AS 568A-311	0.537	13.64	±.007	±0.18	0.21	5.33	±.005	±0.13
AS 568A-312	0.6	15.24	±.009	±0.23	0.21	5.33	±.005	±0.13
AS 568A-313	0.662	16.81	±.009	±0.23	0.21	5.33	±.005	±0.13
AS 568A-314	0.725	18.42	±.010	±0.25	0.21	5.33	±.005	±0.13
AS 568A-315	0.787	19.99	±.010	±0.25	0.21	5.33	±.005	±0.13
AS 568A-316	0.85	21.59	±.010	±0.25	0.21	5.33	±.005	±0.13
AS 568A-317	0.912	23.16	±.010	±0.25	0.21	5.33	±.005	±0.13
AS 568A-318	0.975	24.77	±.010	±0.25	0.21	5.33	±.005	±0.13
AS 568A-319	1.037	26.34	±.010	±0.25	0.21	5.33	±.005	±0.13
AS 568A-320	1.1	27.94	±.012	±0.30	0.21	5.33	±.005	±0.13
AS 568A-321	1.162	29.51	±.012	±0.30	0.21	5.33	±.005	±0.13
AS 568A-322	1.225	31.12	±.012	±0.30	0.21	5.33	±.005	±0.13
AS 568A-323	1.287	32.69	±.012	±0.30	0.21	5.33	±.005	±0.13
AS 568A-324	1.35	34.29	±.012	±0.30	0.21	5.33	±.005	±0.13
AS 568A-325	1.475	37.47	±.015	±0.38	0.21	5.33	±.005	±0.13