This Saddle Rail Mount kit allows you to clip the Flare rear light under your saddle. The mount fastens to the rails of the saddle with the red band fixing to the mount and wrapping around the rails to secure the light to the saddle.
"I bought this to attach my Flare as the angle my seatpost made the light point slightly downwards with the standard mount. This points the light horizontally and worked perfectly in that regard.
There is a but..... But, I have a Brooks B17 Narrow Saddle and struggled to attach this mount because the elastic part provided wasn't really long enough to reach around the rails (which are slightly further apart than on most saddles). I did manage in the end although the elastic was stretched further than I would have liked. I used it like this for maybe a month, but one day it fell off, taking the Flare with it. Needless to say I only noticed at the end of a longish ride through London, so now I'm an expensive light down. This product has actually cost me money as I've had to replace the light.
Just a cautionary tale anyhow, I'm sure it works fine on narrower railed saddles."
Cons: Unadjustable, Poor Fit, incompatible with wide-railed saddles