"These compression elbows are great quality at a great price. As a time served plumber I've fitted many of these and I've never had one fail on me yet. If your looking for a compression elbow these won't let you down. I don't see any sense in paying more for other brands when these are up to British Standard and do the job well. I highly recommend them."
"...and don't buy these poor quality elbows! At least half of them aren't even exactly 90 degrees, tightening them isn't easy as you can't get any purchase on the body and the olives are rubbish. The kuterlite elbows (also available at screwfix) are twice the price but infinitely better!"