How to install a tritium vial in the FACTOR (see description) Media

The correct tritium vial size for the Factor is 3mm x 22.5mm, and they can be found on eBay. Some tritium vials run a hair bigger than the slot in the Factor's "flip lever." When this is the case, don't try to force the vial in or it's almost SURE to break. Instead, take a small file like the one shown (less than 3mm wide to fit into the slot - available on Amazon) and file one side of the slot down until the vial fits SNUG. You don't want a loose fit, nor do you want it tight. File in 5-10 second increments and keep checking the fit until all it takes to insert the vial is a fairly gentle press. Keep the file SQUARE (perpendicular) in relation to the slot for a nice finish. Once the vial is in the slot it's well protected.