Mct Boxes are moulded in polycarbonate and are therefore strong as well as autoclavable. One size can hold 64 MCT's of 1.5 ml. & the other can hold 100 MCT's of 0.5ml.. These boxes are designed to work at temperatures rising from -190 degree centigrade to +121 degree centigrade. The transparent cover provides a good view of the contents inside & is numbered for better inventory control