15 ml vials were created for researchers who required pooled samples for analysis or who are homogenizing larger samples. This product was designed for the difficult job of dry grinding 15 lyophilized corn kernels for field trials. These 15 ml polycarbonate vials are extremely durable. They can be submerged into liquid nitrogen and immediately used for homogenizing. Each case comes complete with 100 polycarbonate vials and 100 unlined polypropylene caps. 15 ml vials work best with 7/16" stainless steel grinding balls.