"I would recommend these over any "copper, or brass fittings" John Guest Speedfix is the best on the market, I have used over 400 JG fittings of all sorts and NEVER had a leak or even a slight weep of any kind. Although 11 leaks on compression out of 37!!! Don't take the chance use John Guest, I have used it on old and new copper pipe with great success."
""Used this system for the 1st time and will now use this in future in preference to anything else!!! Bought complete set of Joints: Couplers - Elbows - Tee's - Pipe & Inserts. Carefully read the manufacturers instructions and started work. Could not believe how fast and easy it was to complete the job and so neat. Not a single drip from any of the joints. Well worth the money!!!""