The Crain Swivel-Lock Stretcher Driving Head Complete No. 1520-Z includes the driving head only for our swivel-head stretcher. The swivel head has 60° of free swivel for patterned carpet. Depress the built-in lock pin, and you can lock the swivel in 5 positions. Lock in the straight position for square stretching, or at 15° for most angle stretching. There’s even a 30° setting for extreme angles found in “L” shaped living/dining rooms. The push-button stretch lock is conveniently located on the handle for partial stretches. Pin depth is adjusted with two screws in the depth bar of the pin plate.