MAX is designed and built to encourage industry best practices and to provide the patients and practices the best products available. As such, CR-39 is not included in MAX. Polycarbonate, Trivex 1.60, 1.67, and 1.74 are included. In many cases, CR-39 can cost a practice more than Polycarbonate.  However, if you need to have CR-39 included you can create a custom package and on the Material you select for that custom package, you can click on the OPEN button and then CR-39 will appear in the Material dropdown box on the Solution page for that particular package.  It will NOT show up in the Package Builder page and cannot be made as a default material.