MBT couplers require neither bar end preparation to form threads nor bar rotation to effect installation. The bars are supported within the coupler by two serrated saddles. As a series of lockshear bolts are tightened to a predetermined torque, they are embedded into the bar. At the same time the saddles bite into both the bar and the shell of the coupler. Installation is complete when the heads of all of the bolts are sheared off. The lockshear bolts on sizes 10mm to 20mm can be tightened using a ratchet wrench. For larger sizes a nut runner is recommended. Impact tools must not be used. MBT couplers can be used to join imperial, plain round or deformed reinforcing bars.