I needed a holder for my iphone so i could run my gps tracker to track my bike rides. I did some searching on Amazon and found quite a few options. None of the holders i found hard a real secure way of holding my phone.Then i stumbled this Topeak dry bag. It was a little more money than the other holders i found, but the water resistance sold me on it. I don't plan to ride in the rain, but you never know when a sudden rain squall will come along.I tried to install my phone into the bag with it's current protective case -- Bad idea! The phone got stuck in the dry bag and i had to use a combination of force and hand sanitizer (it's mostly glycerine) to remove it. Make sure you remove any case you have on your phone before putting it in the dry bag.The bike-side clip is large enough to fit any bike, perhaps even a motorcycle. Installation requires a screwdriver and a pair of scissors to remove excess length. I left an inch extra in place in case i move the clip to another location or bike with larger handlebars. Note that the mechanism that holds the clip in place is made of plastic so don't tighten it so much as to strip the plastic. I made the clip tight enough so that it doesn't slide around but still loose enough for me to adjust the tilt depending on the sun's glare.Once the clip is installed on the bike you slide the case in place and it snaps in nice and snug. To remove, you press the release and slide the phone off the clip. Very simple.I'm able to control all functions of my iphone while it's in the case. If you want to take a photo you'll need to unroll the zipper portion of the phone to move it out of the way of the camera on the phone.Very happy with this purchase, highly recommended.