1/8, 1/4, 3/8, 1/2, 3/4, 1, 1 1/4, 1 1/2, 2, BSP Bonded Sealing Washers (Dowty). Bonded Sealing Washer - Dowty Type. Sealing washers are used to close the flange / screw against pressure compared to flat washers.
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