Shock Seal Head - 18 mm ID x 50 mm OD Complete assemblies, ready to install into the shock body, Made from 6061-T6 aluminum and the same custom elastomer as our fork seals, All have air bleed holes to help remove air from the oil reservoir during installation, Double-lip oil seal designed to keep out dirt and keeps friction low, Some models have updated designs for easier installation, Includes aluminum body, dust seal, bushing, oil seal, O-ring, internal guide bushing/washer, snap ring and top out bumper, Made in the U.S.A.