Next Generation 25-Pack Sterile Capped Centrifuge Tubes for Pet Semen Shipping, 15ml Molded graduations, threaded tops and liquid tight blue caps Polystyrene is crystal clear Graduations are in increments of 0.1ml up to 1ml and then in increments of 0.5ml up to 15ml Great for freezing extra Next Generation Semen Extender Molded graduations, threaded tops and liquid tight blue caps Polystyrene is crystal clear Graduations are in increments of 0.1ml up to 1ml and then in increments of 0.5ml up to 15ml Great for freezing extra Next Generation Semen Extender Molded graduations, threaded tops and liquid tight blue caps