Review on Black Reclosable Resealable Inch Zipper Packaging & Shipping Supplies by Brandon Plowden

I bought these in black to give me an extra layer of light blocking when shooting in the field with 4x5 film. should be), but they are cheap and fit in 4x5 film holders. My advice is to double or triple wrap them. Your holders have to be lightproof anyway, so that's just a nice added bonus. I was hoping to use them to store exposures, but I don't trust it. If you bring a headlamp to it you can see the light seeping through the two layers. For complete light tightness you will need a triple or quadruple bag. It's still cheaper than other options. It's great for storing loaded mounts when shooting outdoors though.