I use something similar and altered the original to suit me better. I sewed the hoop side of velcro material to the back of the mount and glued the hook side to the phone. With this I can attach the phone and have the PVC cover zipped if it is raining or not if the weather is fair. I have such mounts solidly attached to a couple of bikes and one more attachable for travel, if I get a bike locally or take along a folder. The PVC can crack after a while but most often can be repaired using a vinyl glue, without hampering much operation in the rain. This PVC cracking is presumably is the most annoying part of my current system. A cable can be passed through the zipper and I have a waterproof amp/speaker system on my main bike. For navigation in the rain, though, I found the sound transmitted through PVC good enough.