BIANCHILiner Belt, Fits 1.5" Belt Loop

I wear a size 44 to 46 pants, should I base the belt off the same size or do I need to go bigger?

Do you use this as your pants belt then the duty belt hooks to it?

I wear size 32 waist in pants, but I actually measure 36" where my belt sits? Should I get small or medium?

I have a 32 to 34 waist should i get a 28 to 34?