Gear cranks, 5:1, self locking, chain pull (20' of chain).

Super reliable, we have sold the same unit (with some improvements) since 2003. Can be used for: small runs of rack and pinion vents, ridge roll up systems, roll up vents in gutter houses. Ideal for exterior light deprivation and retractable shade systems. Installation hardware sold separately.

Can also be applied to the Agricultural Trade for Ag Curtain Venting systems.