FLX13 is a tool number (like the part number, if you want to think of it that way) for this flexible extension from Snap-On tools. I don't know if you'd be able to buy this online or not from Snap-On. They may tell you to buy it from the local Snap-On distributor. Check the white or yellow pages in the phone book for Snap-On tools. You'll probably have to set a time to meet them at a shop someplace, they usually have a regular route they keep. Price I am not sure of, I'd guess 20 to 30 dollars though. the price may be available online. I'm sure the website is probably
www.snapon.com not sure though. Great tools, last forever and a lifetime warranty if they don't.
Gilly