Acavallo Arena Aluplus Aluminium Safety StirrupsDescription Made of certified high grade anodized aluminium and fitted with a stainless steel tread. The opening of the stress actuated locking and release mechanism is located a centimetre higher from the tread to ensure that the foot canot slip out laterally by mistake and to prevent sand and dirt from delaying the opening action of the arm in case of an emergency. One size 12cm