How to measure driver size

Got a atactical Al took out the driver and measured the round base, measured in thousands of inch got .818 which converted to 20mm? Does that sound right, was under the impression that most EDC tube lights were 17mm

Sounds normal, 20mm is another very popular size driver.

Ya think I’m just being paranoid, thanks for the info

Just like this in the pill, use the inside of the jaws if the drivers out. Drivers come in all different sizes and almost always be measured in mm’s.

Awesome thanks, on the light i measured the inside of the threads,the driver has to clear them,it read 21mm so i guess it’s safe to say it’s a 20mm driver

Sometimes drivers just don’t fit exactly, usually most drivers can be filed or sanded down 1 or 2 mm to fit some odd size pills.