Use a CoolBox XT Extension Collar when keeping tall tubes such as 3, 4, or 5 mL cryovials, 15 mL or 50 mL centrifuge tubes and blood collection tubes in the CoolBox XT ice-free cooling workstation.  

Place in between the the base of the CoolBox XT system and the original collar.  Magnets on top and bottom provide a secure connection to the base and original collar. 

Dimensions (L x W x H):

Internal: 14.0 x 9.4 x 7.0 cm
External: 20.0 x 16.0 x 7.0 cm