The Fatal mod by QP Design is a token to their commitment to quality. This sleek, gorgeous mod is compact and ergonomic, and will compliment any other pieces by QP Design. The Fatal is designed to work with 21700 batteries, and 18650 and 20700 as well. The battery bay is made of a resistant clear tube, allowing to have your battery on full display. To that effect, QP Design included 4 different battery shrink-wraps (2x 21700, 1x 18650 and 1x 20700) to complete the look of your Fatal mod.