This is an interesting idea that I am still trying to get my head around how I feel about it. RETA Kydex is now offering a light rail customization option for their Kydex magazine carrier (pistol and rifle). The option places a small section of rail on the carrier so that you can attach your pistol light and keep it close at hand without needing to have a light specific holster for your handgun.
On one hand, I can see the utility of this and I think it could be useful for some shooters. On the other, I would much rather have my light mounted and ready. Regardless, this is an interesting product and I am glad to see Kydex benders like RETA Kydex continuing to innovate.
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