Here is a useful accessory from Checkpoint - visual wheel nut looseness indicators. This is a simple but very effective solution for monitoring nut tightening on commercial vehicles. It visually indicates when nuts are loosened - the arrow turns as they loosen. Suitable for trucks, buses, agricultural machinery - anything where wheel tightening control is important. The yellow color of the arrows is clearly visible on nuts and hubcaps. It's made of durable plastic and designed for a long service life. Fits quickly and easily onto any 22mm diameter wheel nuts. Maintenance-free during operation.