Cardboard Spool Caliper

I use a lot of third-party filament that comes on cardboard spools. I've tried many adapter rings, tape, and other methods to make them work well enough in my AMS, but never had great success. I sometimes respool them onto Bambu and older plastic spools, but that's time-consuming and prone to jammed filament. I've had the best success ripping the sides off of the carboard spools and using various adapters to make the cardboard core fit on a Bambu spool. The problem here is that I never know if the inner diameter of the cardboard core will fit on the Bambu spool or what adapter I might need until I've torn the side off of the spool. The missing piece was this spool caliper. Simply close it all the way, drop the feelers inside the spool, then pull open until it stops to find out the exact inner diameter of the cardboard spool before tearing the sides off. You'll know if it's too small for your refill spools, if it's the perfect fit, or what size adapter you&#3