Did a quick test on the quickdraw pro with the 4" coil i use on My Tracker IV. it works on a nickle and my wedding ring they both id 36 ( now this is and air test on the floor of my office) quarter 72-73 I hunt a lot of tot lots so I don't care about depth to much there also the lower rod of the BH IV WORKED .SO EASY SWAP OF RODS. Now that I know this small coil will work.I'M liking it more and more. any deep hunting I just switch back to the 10" coil