I have a German Hansa contact printing frame. It is primarily designed for 135 film and allows you to clip film strips of 6 frames between a forked tongue prong at either end.
I purchased this as the centre glass is completely clear of anything, meaning I can use any other format, which I do.
As 135 film is my bread and butter, it was important that the unit be really fast and accurate with that format.
When using 120 film I cut into appropriate lengths and use removable magic tape to hold the film on the glass. The same goes for 4x5 film and 8x10 film. So you can see it is very versatile.
I contact all of my colour films, otherwise I don't have a ready and accurate reference when printing.
If in a position where I don't have a professional contact frame, then I use glass with this method.
Tape a big L down one long side and an adjoining short side using a cloth or duct tape type of product, this is your alignment for the paper in the dark.
Next, tape the film to the glass using removable magic tape, removable is the operative word in the operation here. From here it is a simple thing to align a sheet of paper in the dark, turn it over and place it either on some dark foam, or layers of dark cloth.
The Paterson contact frame thingys are quite alright, but they (in 135 format anyway) require you to slide your film under a hard plastic holder. Apart from the fact that your film really gets some vicious handling when things get hot and sticky, they cannot be used for anything else except for the chosen format.
Paterson make 120 ones as well, I have one or two, but I haven't used those in about a decade. Whereas the Hansa was purchased about 35 or more years ago, and more or less, is the only contact frame I use.