Precision Gunsmithing offers a few modifications for the popular Surefire Fury that make it easier to hold on to and cheaper to feed. They machine a series of grooves around the circumference of the light so that o-rings can be retained in the grooves. This greatly improves the grip on an otherwise slick light.
They can also bore and polish the inside of the light to allow it to accept a rechargeable 18650 battery. In addition to the benefits that come along with being rechargeable, the 18650 gives 15-20% more runtime versus CR123A primary batteries.
These are some very simple and functional modifications for a great light.The o-ring groove service costs $42 for regular guys like me and $35 for LEO and Military members. The price includes shipping and o-rings. If this is your duty light, Precision Gunsmithing can complete the work in as little as 48 hours.
Precision Gunsmithing offers several other modifications for flashlights including machining for tritium locators and pocket clip installation. Check out PrecisionWorks.co.