LeBipBip solar vario from French company Stodeus is a wonderfully sensitive audio vario with a host of other features.
A built in solar panel generates 10 times the energy needed to run the unit, so it will never let you down, and never run out of juice. Designed and tested in the french alps it is the go to hike and fly companion.
Also a LED lamp blinks with your climb rate which is useful for PPG pilots in particular.
Completely configurable in sound and sensitivity, LeBipBip also incorporates a near lift proximity buzzer so sniffing out the light lift is even easier.