<p><b>This Listing is for a Complete grinder wheel set. This drive wheel is a 5/8" bore with a 3/16 keyway and set screw.</b><br> <br> Material: made of billet 6061 aluminum.<br> <br> The 2" wheels are 2" in diameter and 2" wide. They have pressed in sealed radial ball bearings and contoured edges to aid with belt tracking (these wheels are typically used with a flat platen attachment on the belt grinder) There is a spacer between the bearing to help prevent over tightening.<br> <br> The 4" tracking Wheel is 4" diameter and 2.5" wide. It is crowned to help with belt tracking and it also has the spacer between the bearings to prevent over tightening.<br> <br> The Drive Wheel is 5" diameter and 2.25" wide. It is crowned to help with belt tracking.<br> <br> The inside diameter of all bearings used is 1/2". Make sure the Method you use to mount the wheels (I just use a 1/2 bolt with no washer and a nut on the other side) does not make contact with the inner and outer races on the bearings at the same time causing it to bind.<br> <br> <p><b>Package included : </b><br> <br> 1pcs 5" drive Wheel (with 5/8" Bore) <br> 1pcs 4" tracking wheel<br> 2pcs 2" idler wheels.<br> <br>