Keep corrosive water and contaminants off your bearings with an airtight hub chamber. Features an easy to install diaphragm that is pressurized with a hand pump to 5-10psi. Positive pressure keeps bearings in good working order, allows you to see at a glance if you have a positive seal and future bearing failures can be immediately detected. Universal kit comes with three different inner dimension size shims and eliminates the need to measure your spindle. Includes a chrome air cap, stainless steel bushing, Super seal™, diaphragm, sport needle, bonding agent and shims One kit per hub