This is an inside magazine tube for the Marlin model 60, 99C, & 990 rifles. It replaces Marlin part number 507522. It is 20 7/8" from the tip of the knurling to the end of the tube and 22 1/8" overall. It fits serial numbers that begin with 11 and go through 25 (outside tube "J" notch length must be 11/32"). We had these made with a metal follower instead of plastic.
If your serial number starts with 26+ or there is NO serial number, you need part number 607222 found here.