MPL9-Bat (BR535) is spare battery kit compatible with Vesala MiniSonde MPL9-10, MiniSonde MPL9-33, MiniSonde MPL7-10 and MiniSonde MPL7-33. Kit includes 10 pcs 3.0V Lithium cells in a handy plastic box. Typically one cell enables up to 6 hours of service time after which it is discarded. These cells are not sold separately.