Mounts onto a 3/4" EMT vertical guide post for easily lifting and lowering roll-up sides on your tunnel. Built-in automatic brake holds sidewall at the desired height for better tunnel ventilation. Durable, weatherproof construction and stainless-steel handle will last for years. The drive shaft fits neatly inside 3/4" EMT pipe for neatly winding up greenhouse plastic. 4:1 gear ratio. Maximum sidewall length: 300 ft. EMT pipe not included.