MetalTech 21.75 in. x 10 in. x 29 in. Aluminum Adjustable 3-Rung Ladder Jacks for Scaffold Extension Walk Boards, Ladder or Plank

It is compatible on either side of the ladder. It can be used with planks up to 18 ft. W and are welded and riveted for added safety. It supports up to 250 lbs. and offers 8 notches of angle adjustment.