Instruction: Answer the given question by extracting information from the supporting document.

Input:
Question: how long is this cable?
Document: I purchased this USB cable along with my Clarion M309 marine source unit.I returned the cable, because I didn't end up needing it.The Clarion M309 description leads you to believe that there is a USB port on the back of the unit, thus requiring the cable.However, the M309 already has an attached USB cable that is about 3 feet long. If you don't need longer than 3 feet, this cable is not required.
I pulled the USB cable from the rear of the stereo/head unit in my Ford Expedition, drilled a hole in the center console, connected them and screwed everything down. The whole process took about 15 minutes, including pulling out and reinstalling the center console.
Electrically the cable works fine. Unfortunately the threads and lock nut do not tighten. When I pulled my ipod cable out of the plug it pulled the entire plug with it. I had to use wire ties to keep the nut secured. Should have bought the Jensen version.
This is a must have unless you are from another planet. Yes I know nowadays everyone hooks up there phones, connects Pandora while fishing, boating or while dropped at anchor enjoying the sun. But nothing like having what you want at the touch of your fingers and while using the USB Cable you know it charges your Iphone or ipod, right? Couple that with the MW1 remote and it's a done deal baby!
No problems installing in my boat dash. A previous reviewer said that the attaching nut would not hold. I had no such problems. This product is designed so that you have a stationary plug on your dash...yes you can use the one that is attached to the stereo...if you want go digging for the cable hanging under the dash every time you want to plug something in. This makes a clean connection convenient and has a waterproof cover.
I was very pleasantly surprised when I received this extension cable that it had a very user friendly installation system. All that is required is a 1 in drill bit. I drilled a one inch hole in my mounting surface, fed the cable through and secured it to the surface with the nut provided. the body of the plug end is threaded and will hold in media up to 1 1/4 inches thick. this is a very handy accessory to use with the Clarion head unit for a clean installation
it's used on a motorcycle faringeasy to install and convenient for those stereos with USB port on the rear
This will prevent the plastic nut from coming loose accidentally or through wear/use, but makes it possible to remove in the future if you choose to do so.
This cord helped clean up my helm station and makes iPhone charging and connectivity very tidy and secure. I recommend it.
The port is VERY tight and the cord end is loose. It doesn't work! It looks great but worthless. I am considering ordering another one since I now have a hole in my dash.
Answer: The cable itself is 60" long. I didn't measure the plugs just the wire.