15mm X 3/4" Female Tap Solder Ring - M-SRTC-15-34 Are manufactured from copper and copper alloy. Fittings are designed for jointing copper tubes to BS EN 1057 in hot and cold water services, in small bore and minibore central heating, low pressure steam heating, and in vented and unvented closed circuit heating systems. WRAS approved. Manufactured to BS EN 1254 Part 1