Grooved washers for 1 3/8" ARMCO plugs. Sizes 41x35x3mm With concentric grooves + expanded mineral graphite coating on both sizes of the sealing surface. 316 pcs. Grooved washers for 1 1/2" ARMCO plugs. Sizes 41x38x3mm With concentric grooves + expanded mineral graphite coating on both sizes of the sealing surface. 264 pcs.