You want an open or a closed holster? Want an variety of colors to chose from? Attachment methods?
My favorite holsters are the one's from Spec-Ops brand gear. Available in different colors/patterns, uses MOLLE webbing for versatile attachment options (belt/pack/sling/whatever). All mine have held up extremely well. Also, Surefire has some, but honestly, Spec-Ops makes the better product. They have one open pouch version also for bigger lights, like the M3.
I have carried my 6P defender in one of these vertical holsters: http://www.blade-tech.com/Light-Pouches-c-293.html on duty for the past few years and have really liked it. These will also accept solarforce bezels. If you purchase one of these, you might want to wrap the screws with teflon tape to prevent losing them, as after awhile the screws may loosen. The adjustable tension is really slick and allows you multiple levels of tightness.
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