However, be aware that the die size of your emitter needs to be less than 14.5mm in diameter to work properly with this heatsink and retain the ability to use the maglite's twisting focus mechanism.
recommend you look up other people's mag lite mods that are on here.
does yours have a D as the first letter/number in the serial number? Haveing a D is common, apperently raelly old ones don't have teh D and are a different size internal diamiter