This is a rechargeable replacement battery for Sennheiser / EPOS DECT wireless office headsets, identified by the supplier code CS-SBP100SL. It replaces the original Sennheiser battery BATT-03 (part 504374) and fits headsets including the OfficeRunner, DW Office, DW Office ML, DW Pro 1 and Pro 2, D10, MB Pro 1 and 2, SD Pro 1 and 2 and SD Office series. Headset batteries lose capacity after a few years of daily charging, leading to short talk times; fitting a new cell restores all-day use without replacing the whole headset, which is a cost-effective fix for call centres, reception desks and busy offices. Published specifications for the CS-SBP100SL are 3.7 V, 180 mAh (0.67 Wh), lithium-polymer chemistry, measuring 37.0 x 17.7 x 4.77 mm. Replacement is normally done by opening the battery compartment of the headset and plugging in the new cell's connector. Charge fully before first use, and recycle the old battery responsibly.