These are preserved and Vacuum packed. 
Room temp storage (no need to refrigeration), and can use any time as required. 
3 months storage life, unopened. 
ADVANTAGE
·  All specimens unconditionally guaranteed
·  Extended shelf life with Vacu-Pac packaging
·  Safe to use
·  Odorless and nontoxic 
·  99.7% Formaldehyde Free 
NASCO-Guard® Specimens allow students to work unhampered by the odor and messiness associated with formaldehyde, and special ventilation is not required. 
Dissection labs become a positive experience for all students when NASCO-Guard® odorless, nontoxic specimens are used.