I’m just about to fit some new radiators and I’ve purchased some of these Drayton drain off valves to place in front of the lock shields.
https://www.screwfix.com/p/drayton-15mm-compression-x-1-2-bsp-male-taper-drain-off-tail-piece-50mm-polished-chrome/3450R
I haven’t applied any PTFE yet but...
