Fanny Pack Holster - Proof of Concept

I have found a variety of holsters on ebay and many have button release retention systems that would be a better option for you.
The problem is that I need to mount the holster inside a fanny pack and most holsters are not adaptable for one reason or another. It's a very tight fit inside my Fanny pack which also holds to additional magazines.

With the holster setup that I have now I can draw one handed just about as fast as I could a holster worn at my hip and that still leaves my left hand free to ward off an attacker. But I am looking for ideas for an additional retention system in addition to what I already have. So thanks for the links.

The problem is that it is too hot to wear while riding a bicycle when the temperature is much 60°F.

I've been carrying with this fanny pack holster since May 2022. It's out of my way when I ride my bike and it's also about as quick to draw from as a belt worn holster at the side. I can also draw one handed with my fanny pack holster leaving my left arm free. I haven't had any issues with the pistol coming out of the holster since I added the external spring. The new Sig holster design also works better than the original design. I still may add a secondary retention system for redundancy. The only change that I plan to make is to increase the size of the magnets in the holster frame that secure the side flaps. At the moment they are only 18" cubes.