The VL 25500-125 Li-ion (lithium-ion) cell is capable of operating at temperatures of up to +125°C, which extends its use into the design of MWD (measurement while drilling) tools. The lithium cells are integrated into ruggedised cylindrical MWD battery systems, known as "Staves", which are then incorporated into MWD tools. Capable of charging and discharging at extreme temperatures, the cell will safely withstand temperatures up to +135°C, a major leap in operating temperature from the current maximum of +65°C. Saft also developed the LSH 20-150 primary batteries for MWD, operating at up to +150°C.