PC, PP screw closure, silicone gasket. Bottles feature wide-mouth sealing cap closure, clarity and mechanical strength. 250 ml bottle is rated for speeds up to 27500 x g; 500 ml bottle is rated for speeds up to 13700 x g. 1000 ml bottles have a multi-part lid and is rated for speeds up to 15800 x g. When using the 250 ml bottle in the Sorvall GSA rotor, use NALGENE centrifuge bottle adapter (Cat. No. DS3125-0250) available separately. For proper performance these bottles must be filled to at least 80 % of the total capacity. Autoclavable, transparent.