Acavallo Adult Arena AluPro StirrupThe stirrup bow is made of aluminium, while the opening arm is made of a special polyamide material. The stirrup pad is made of polyamide, too, and the tread is fabricated from stainless steel. The AluPro model, in principle, provides the same function as the Arena HiFlex, but it is based on different materials. Main Features Unique, stress actuated locking and release mechanism located between the lower end of the outer, pivoting stirrup arm and the