Battery sled. Features: Optional L-Mount battery sled for the Sound Devices MixPre-10M, MixPre-10T, MixPre-6, MixPre-6M, MixPre-3, and MixPre-3M audio recorders. This sled holds two hot-swappable, Lithium-Ion batteries (not included). The sled is compatible with Sony L-type batteries.