SCA-STA Scale Defender provides 100% recyclable, compact and low maintenance protection from limescale. Complete with 15mm and 22mm fittings. * Whole house limescale protection * Easy to fit * 100% recyclable * No maintenance * Helps extend the life of household appliances * 100% safe for drinking water * Refill cartridges available (Code 51478) McAlpine Scale Defender 15mm & 22mm Starter Pack. Scale Defender Starter Pack complete with 15mm & 22mm fittings designed to stop limescale. McAlpine Scale Defender tackles limescale while protecting your home and your pocket. The small but powerful Scale Defender is affordable, and safely seals and removes calcium, protecting your boiler, drinking water, appliances and entire home. McAlpine Scale Defender can save hundreds of pounds as it keeps your heating system more efficient and helps prolong the life of pipes, fittings and appliances.