Backcountry Access Polycarbonate Crystal Cards Raw. Snow crystals placed on the card become recognizable and sizable. Ideal for sunnier climates the BCA polycarbonate crystal card does not absorb as much radiation as the aluminum crystal card which allows you to study snow crystals longer and more accurately. This small yet very informational tool will take your snow safety skills to a new level. Package Contents: Backcountry Access Polycarbonate Crystal Card Backcountry Access C2018003010: Polycarbonate Crystal Cards Raw