Note: the specimens are initially preserved in the best preservative possible: formaldehyde. Problem is, as you would know if you've done dissections before, formaldehyde is an obnoxious-smelling (as well as toxic) liquid. That's why our supplier has displaced the formaldehyde with water, then displaced the water with a glycol solution using a process that is patented under Patent No. 357382. You enjoy a very decay-resistant specimen, but without any toxic fumes or messy liquids. Specimens store indefinitely when kept in a plastic bag, but we recommend that you use them within a year of purchase for best quality.