Prologo zerotri pas tirox saddletirox rail light alloy steel highly resistant to traction and torsion for its physical characteristics and light weight is used in the aviation and aerospace industry t irox then turns out to be a rail with a good balance between weight and strength that doesn t fear the normal stress that addresses a bicycle pas system the pas system is a processing of the base of the saddle the hole or channel has been designed to eliminate pressure to a zone of support