I ran this when I started. But I started riding switch and my ability to look backwards is a lot better... riding at night helps too.

Chums Rearview Mirror https://www.amazon.com/dp/B003CK11P8?ref=ppx_pop_mob_ap_share

I put this on a retracting lanyard... as I wear wrist braces, and I've ate shit enough times to think anything mounted to my wrist will only help break it.