Bumper Instructions [ Quality Fabricators® [Tracksuit 1-877-637-3712 Bumpers aiE e 1. 5"Bumper (x4) 2. 4" Casters (x4) ASSEMBLY INSTRUCTIONS 1. Insert Bumper between the top of caster and the bottom of the frame conical side up. Tools Require ct Adjustable wrench {or 1/2, 11/16 box wrench), hammer.