The ACS Maindrive is an integrated 1-1/8 inch headset built to 45/45 Campy spec, which is the standard almost every modern BMX frame with an integrated head tube is cut to. If your frame takes an integrated 1-1/8 inch headset, this drops in.

Construction is alloy with sealed bearings, so the weight stays down at the front end and the bearings are shielded from the water and grit that usually finish a headset off.