Just so happens that I have a Kodak "Target Six-16" camera sitting here. The frame gate on my camera measures 108 mm. x 60 mm., or 4 1/4 x 2 1/2 inches. The length of the spool is 72 mm measured from the outer surfaces of the flanges, and 67 mm. measured from the inner surfaces of the flanges. The core diameter is 7 mm. The flanges themselves are 2.5 mm. thick. It is substantially larger than 120 roll film. I got this camera at least 40 years ago and I've put exactly 1 roll of film through it. I can't remember how many exposures I got from that roll. Six -16 film has been out of production for at least 20 years now, so it is unlikely that I'll ever run another roll through it again. If you're thinking of using it, I'd give it a pass. There are plenty of similar cameras that use 620 and 120 roll film out there selling for only a few dollars. Obviously 120 roll film is still available. Six-20 size has been out of production for a good long while now too, though you may be able to find some from specialty film dealers. The film and paper backing for 120 and 620 are sized identically, only the dimensions of the spool itself are different. Some of the old 620 cameras will accommodate the 120 spool, some won't. No matter, it is a simple matter to re-spool 120 roll film onto a 620 spool. All you need is a darkroom or a changing bag, a supply of 620 spools, a spare 120 spool, and a little bit of tape. Six-20 spools come up on eBay once in a while, but the prices asked are often ridiculous. Whole cameras with a spool (and sometimes even with old film inside) can be found for less than the asking price of the spool alone at garage sales, flea markets, and thrift stores.