AW IMR: 48.75mm., AW 14500 protected: 50.93mm.. I bought the the IMRs for my 2 NiteCore EZ AAs as my protected 14500 were too long for these lights. They work in all my AA lights EXCEPT my EZ´s, (first edition) with these batteries when I screw down to bottom the light turns on to low and no more. Fun.Don't know the exact measurement specs, but my AW "safe chemistry" orange label LiMN 14500's are shorter than the standard black label 14500's with the protection circuit, and thus fit more comfortably in my Minis whereas the black labels have a very snug/tight fit that I'm not comfortable with.