These two materials were chosen as labware raw materials for their durability, broad chemical compatibility profile, and wide range of use temperature. Polymethylpentene offers a higher level of transparency (comparable to glass) but is slightly more brittle and therefore somewhat more likely than polypropylene to crack if dropped. Chemical or environmental factors in some applications may strongly indicate the use of only one material- please refer to laboratory plastics reference materials or call Thermo Scientific Laboratory Products Essentials technical support for assistance.