Hi Marc,
The answer to that goes on for pages and pages and pages ... 15 pages for Ideal twist-on wire connectors (wire nuts):
http://www.idealindustries.com/media/pd ... ations.pdfYou can also check each individual type (Twister, Wire-Nut, Twister Pro, Wing-Nut, etc.) here:
http://www.idealindustries.com/products ... /twist-on/An example is the Wing-Nut, 451 Yellow, 452 Red, and 454 Blue here:
http://www.idealindustries.com/products ... ng-nut.jsp , however, that does not give you all the combinations, only the minimum and maximum sizes and minimum and maximum combination, see first link above for all listed combinations - there are 152 listed combinations for the 452 Red Wing-Nut in that chart (
http://www.idealindustries.com/media/pd ... ations.pdf ).