That gun has been made by a number of manufacturers over the last thirty or so years. It was originally called the AR7 and was made by Armalite (IIRC) and then by Charter Arms still as the AR7. There may have been more. I bought the Charter Arms version back in the 1970's. It was as already described. I found it handy, reliable and acceptably accurate. My son has it now on his boat in California.
There used to be, and maybe still are any number of aftermarket doodads for AR7 - extended magazines, different stocks, scopes, etc.
FWIW - though they are not available now, for my money the Springfield Armory M6 Scout survival rifle was a better buy (they can still be found if you look a bit, though prices are probably high.). Springfield has had them in and out of production a number of times, so they may yet show again. (all steel, O/U, .22LR or .22 Hornet and .410 shotgun. Ammo can be stored in a magazine in the butt stock.)
Pete