long-term performance—even in tough environments

Durable outdoor construction: Powder-coated aluminum frame with stainless steel springs

56 3/4" opening

Built with a 1

and 10x20 ft (M36) are the standard sizes

Alton | Bayliss XL Roof Vent Opener Piston Replacement Electric Heater long-term performance—even in tough environmentsThe Bayliss XL Piston or Power Tube is a direct replacement component designed specifically for the Bayliss XL Automatic Greenhouse Vent Opener. If your current unit is no longer responding as it should, replacing the power tube is a simple and cost effective way to restore smooth, temperature driven vent operation. This tube contains a heat sensitive wax core that expands as temperatures rise and contracts as they fall, driving the piston that opens