Based on this product's specifications, here are some alternatives and similar models
Automatic Air Vent FERRO O06 1/2" for Heating and Plumbing Systems
Summary description:
FERRO O06 is a 1/2" automatic air vent designed for removal of trapped air in heating and plumbing systems. It provides continuous automatic venting to improve circulation and prevent airlocks in radiators, boilers, and pipework. Suitable for installation on horizontal or vertical runs where a compact automatic air eliminator is required.