This useable ice packs is sturdy and made of 100% BPA-free food-grade HDPE shell. Filled with non-toxic gel. The slim, lightweight and durable design keeps your insulated lunch bag colder with longer time. Fits into all types of lunch bags, lunch boxes, coolers and grocery totes. Great for using in tight spaces or stacking several together for greater cooling power. 3 9/10" L x 5 9/10" W x 8/10" H