Opinion on Digitec laser collimator

I just bought a C11 and have the Bob's Knobs but was thinking of buying the Digitec laser collimator. Does anyone have one and what do you think of it? Does it screw into the back of the C11 after removing the 1 1/4" visual back or do I need a 2" adapter? Thanks, Gerry

I have the Kendrick one. Works OK. I find it's almost as easy just to do a traditional star collimation as to use the laser.