Designed to fit many types of 3.5" sliding type screen changers. Made of 4140 pre hardened alloy steel. Specs = .874-.876" thickness, 3.860" major OD, 3.570" minor OD and a radial hole pattern consisting of 93 1/4" holes with 90 degree countersinks on both sides. Contact us for quantity discounts or to apply for net 30 terms.