Thanks found the size. 32 x 32 x 6mm. Just rang the local supplier and they only get 30 or 40mm. Anyone know of an online supplier who might have the correct size?
Mine is around 32 x 32 x 6 bright mild steel, closer to 1.250" x 1.250" x 0.250". The front edge is usually machined at an angle so you can bend past 90°.