These valves are angled, and would normally be used with designer towel rails and radiators. They are also used with dual fuel towel rails where you will need 2 X T Pieces and a pair of angled valves, one on each side so that the rail will look symmetrical.
 
If you have one T Piece you will need to buy one pair of angled valves and one pair of straight, however this is a very expensive way of doing it and also will waste 2 valves.

With these NEW modern radiator valves we offer the very best in design and quality at a very reasonable price. They are certain to add the finishing touches to your heated towel rail, to deliver graceful comfort and the ultimate in modern style to any home.