Silverline Radiator Bleed Keys Clock Type 2pk

Amazon

Hard-wearing solid brass construction Easy-grip butterfly-wing handle Bleeds air from radiators Improves central heating efficiency, Weight: 0.0440924524 Pounds, Manufacturer: Silverline

Electrical World

Solid brass clock-type with easy-grip butterfly wing handle. Bleeds excess air from radiators. Helps improve efficiency of central heating system. Fits most modern domestic radiators.