and 10x20 ft (M36) are the standard sizes

Built with a 1

100% UV protected 4mm twin-wall roof panels provide diffuse light for even growing

56 3/4" opening

Designed for compatible Vego Pacific and Victorian greenhouses

Alton | Bayliss XL Roof Vent Opener Piston Replacement Electric Heater and 10x20 ft (M36) areThe 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