Compatable with: the replacement discs diameter is 20mm, as the optimyst parts, it fit for electric heater. Application: If your optimyst fire lack of mist or stop mist, the transducer disc may help to solve the problem. Replacement transducers disc for optimyst fire If your Opti- fire had stopped misting, it possible problem as the transducer. Try to replace the transducer disc, it may help your electric fire smoke effect come back. Long : The transducer discs with premium material, anti-aging, anti-, can last a long to 5000hrs. Replacement transducer disk Great replacement part for smoke effect fire.