ROD HOLDERS

This is a simple way to measure the diameter of your rocket launchers if you don't have a pair of calipers or micrometer. Take a piece of fishing line or string and wrap it around the tube in the location you are going to mount the holder. Mark the circumference and then lay it out flat and measure with a ruler or tape measure.Take that dimension and convert to a decimal and divide that by 3.141 and that will give you the diameter you need.
Example- If you get 5" 31/32 that would be 5.968/3.141=1.900 size
2.140 would be approx. 6" 23/32
2.375 would be approx. 7" 15/32
Or just use this calculator