FourfingeredjakeHey there Fourfingeredjake, Thanks for your question. The zipper on the main mesh compartment is actually the same type of zipper that is used on the water resistant side pocket. The zipper has a polymer on the tape of the zipper chain that allows it to be RF welded to the mesh main compartment. Water resistance is not needed for a mesh compartment obviously but the end result is a very clean looking design without stitching. Hope that info helps!