i use the bel sti-r which is the built in unit. it has the laser blocker and radar detector detector blocker so it blocks the cops that can detect radars as well. ive had a bunch of radars k40,v1, 8500 and this bel beats them all. im able to pass by cops that are lasering me at 85 mph in a 65 mph zone because they never get my speed.i love my radar detector. i give it big hugs when i get in the car. the problem with them in canada is that there is too much interference with the plows putting off ka, and other service trucks using false signals