The Z446-750-A50R by Hermle is a 2-pack of 7 x 50 ml round-bottom tube inserts for the Z446-750 swing-out rotor on Hermle Z446/Z446-K centrifuges, enabling up to 28 x 50 ml round-bottom tubes per run at 4,000 rpm / 3,434 xg (4,500 rpm / 4,346 xg on Z446-K).