My laptop battery was failing fast, with insufficient power to operate properly leading to strange effects such as the mousepad only working erratically.
Bought and fitted this replacement and it's now back to health.
The battery came with a wee screwdriver and a pair of picks for opening the casing - no instructions for fitting, but there are loads of these on YouTube (my Dell had slightly more/different screw positions) - and fitting was comparatively easy.
First switch-on after fitting took longer than normal, while the system ran diagnostics etc, but now back to normal.