I needed this battery for my small MURO-MR100 which is a tiny all-in device (MP3 Player, FM radio, stereo recording from aux source or radio, recording from an in buil mic, saving files directly in MP3 with features like equilizer etc.This SONY battery even surpasses the original OEM battery which came with this device. Before trying this SONY battery, I had tried other batteries but either they were cheap imitations or simply didn't work at all. On occasion I even returnted back some of them to the supplier.I am delighted by this new SONY battery... it retains charge even in cold conditions, charges very fast, fit exact dimensions (some of the batteries I had tried in the past had a thicker plastic cover which made the battery stuck in my MP3 player). and lasts a long time on one charge! I never had any problems with this excellent battery! Highly recommended. Thanks