New injection molded spools are also available here.
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The Film Photography Project 620 spools are nicely made. The plastic is smooth and strong and well-injected- no sinks, spurs, flashing, etc. All dimensions are good EXCEPT that they are taller than standard 620 spools. The side flanges are thicker than the metal flanges on old 620 spools; I assume this is simply a material requirement. They couldn't narrow the internal width or the film with paper simply wouldn't fit. So they added the extra material to the outside.
I asked the FPP people about this before getting some and they said that they had heard of problems with Kodak Medalist cameras, the camera I use. I ordered some just for fun. They do fit in the TAKEUP side of a Kodak Medalist, but they DO NOT fit the FEED side. The spools are too tall.
I use the FPP spools as takeup spools. I roll onto metal spools for the feed side. Works out fine.
The actual increase in height (or width?) is about 1.3mm, or 1/16" inch. I think that most cameras that take 620 will have no problem with this. Put a metal spool in both sides and see if there is some slop.