For a wheel to perform properly, it is important for the rim to be centered between the locknuts of the hub, or "dished". To check this, and to make precision adjustments, a wheel alignment gauge (also called a "dishing tool") is a must. The WAG-4 allows easy checking of the dish on road, mountain, or BMX wheels from 16" to 29". It works with any hub width and its innovative design even allows it to be accurately used with the tire still on the wheel. An accurate and truly versatile wheel alignment gauge that belongs along side every truing stand.