These are 45cm, full-extension, side-mounted, ball bearing runners.
If your drawers and cabinets are square, and a good fit, proper runners like these are the way to go (rather than fitting wooden rails for the drawers to slide on). They feel secure, smooth, and let you pull the drawer out all the way when opening.
My only regret is that these runners are heavier than needed, and we could have got away with some lighter duty runners.
£6 per pair from Screwfix.