ION Omni Wheels are compatible with the REV ION System and come in a wide range of sizes, all featuring the MAXSpline bore. Other bores are possible with a separate MAXHub. Rollers for each wheel size are unique, which ensures perfectly circular wheels. Wheels have a 3-piece hub construction, assembled using self-tapping screws. The outer hub rings are aluminum with dowel pin recessed areas completely within aluminum part for stronger roller retention. Similar to ION Traction and ION Grip wheels, wheel spokes have a bolt circle of #10 clearance holes patterned outward at 1/2in pitch and also have a 3/8in wide nut groove, which removes the need for a wrench when utilizing the holes on the spokes.