About this item Material: white film nylon glass fiber with top quality ceramic balls Size:nylon gasket thickness is 1 mm,ceramic balls diameter is 1.588mm Suit for brand folding pocket knives bearing,this bearing can not be installed if your folding knife does not come with the unit bearing position. If you need to install or replace the bearings, then you need to disassemble your tool to measure whether the outer diameter and inner diameter of the hole to install. You can get 2 pieces ( One knife needs two pieces bearings )