Rugged aluminum I-Beam frame. Top read window for convenience. Beveled end caps protect vials from shock. No. 540-24: Length: 24 In., Material: Aluminum, Magnetic: No, Number Of Vials: 3, Pkg Qty: 1, Package Type: Card No. 540-48: Length: 48 In., Material: Aluminum, Magnetic: No, Number Of Vials: 3, Pkg Qty: 1, Package Type: Card