New bike, needed new cadence and speed sensors. These are the latest iterationreplacement for the previous model, GSC-10
I think the price is higher for the two modules, and that's really the only negative that I see.
Mounting was super easy - no magnets to align, no sensor arm to set, just use the included o-rings (several sizes included) for the cadence sensor. The speed sensor sort of wraps around the hub (can use either front or rear).
I had zero issues pairing with an Edge520, I set the wheel diameter to the right value, the speed sensor's just as accurate as the GSC-10 on another bike, or the Bontrager module on a third bike.
No issues at all in the several months this has been in use.
This product is a total game changer. I really don't know how I ever rode without one. I live in Houston and it can be a bit scary at times getting buzzed on the surrounding country roads. The Varia lets you know when a car is approaching so if you're taking up a full lane, rotating in a paceline, chit-chatting side by side, etc. it allows you to time to make (or not make) a move. The integration with my 520 is perfect and not visually distracting or cumbersome on the screen. You need one!!!!