Oh, the "joy" of snap-freezing samples in dry ice. View this to remind yourself of all the "joys" you experience when inserting tubes directly into dry ice. Then......see how you can improve this experience by using a CoolRack thermo-conductive tube module. The CoolRack becomes the same temperature as the dry ice and allows rapid, uniform and EASY snap-freezing. Standardize your procedure with a CoolRack.