CRAIN 510 LEVER EXTENSION TUBEThis upgraded lever activated extension tube lets you make quick adjustments on the fly while stretching carpet! Simply raise the top hand lever to unlock for fast extension or retraction of the tail. The bottom floor lever will unlock when the stretcher head is raised, allowing you to easily extend or retract the head. The No. 520 is designed to work with almost any power stretcher with standard sized poles (1 3 4" inside diameter). Hand lever