Whirl Pak 4oz / 118ml Sterile Bag, Write On, pk 500Polythene bag with tab and wire frame at top that allows the bag to be opened wide and sample to be added easily. - - - Nasco's patented sterile Whirl-Pak Sampling Bags for sampling in the food, dairy, water, sewage, medical, veterinary, environmental, soil, and industrial laboratories. - - - Whirl Pak Bags are now the preferred sampling system in the United States. Their sterility, strength and ease of storage has helped to replace more bulky and costly sterile plastic containers in sterile sampling. - - - The bags are resealed by pulling the tabs and whirling around the wire. - - - Suitable for solids, semi-solids and liquids. - - - 500 bags per box - - - Size: 7.5 x 18.5 cm,,,,,,,,,,,,,,,,,,