I've been carrying a Fenix PD35 TAC with a Thyrm Switchback 2.0. I just received my Olight M2R Pro and being a 21700-sized light (compared to the 18650) the Switchback obviously doesn't fit. Having to revert to attaching a rubber O-Ring for light retention is a big step back after training with the Switchback.

Thyrm says they're getting a fair number of requests for a 21700-sized Switchback, so if you use the Switchback and have or are thinking about getting a 21700 light, let Thyrm know. I'd love to see them bring this to market.