Bottles feature wide-mouth sealing cap closure and clarity and mechanical strength. 250-ml bottle is rated for speeds up to 27,500 x g; 500-ml bottle is rated for speeds up to 13,700 x g. When using the 250-ml bottle in the Sorvall GSA rotor, use NALGENE centrifuge bottle adapter (Cat. No. DS3125-0250) available separately. Before autoclaving, just set closure on top of the bottle without engaging the threads. For proper performance these bottles must be filled to at least 80% of the total capacity.