i had my old flexsmart x 3 for a long time and really liked it. i recently upgraded my old phone to an s21. for some reason the phone wouldnt auto pair to the transmitter and i would have to go through the pairing process every time i shut it off and turned it on again. I chose the km18 because it was similar to my flexsmart. it had a flexible arm to adjust the angle so you can see the display. The reason i needed the arm was that i am using it in my 02 corvette and my power outlet is inside the armrest console by my right arm. I plug the transmitter in and route the flexible arm out the edge and outside the armrest so i can also lock the armrest preventing someone from just stealing it(i often leave the top on the convertible down). unfortunately the km18 has a shorter and less flexible arm so i cant route it back outside the armrest. i leave it under the armrest in the console. It works fine that way but i cant see the display and cant use handsfree talk unless i open the armrest. I dont often use it for talking so its not a big issue, but i really wish the arm was a little longer and a little more flexible. The transmitter sounds good and pairs instantly although i could do without the voice that says "waiting for pairing, device paired" every time. My biggest issue is that for some reason the part that plugs into my power outlet is not tight enough, so if i move it it disconnects constantly. because i am leaving it under the armrest and only touching it to turn it on and off, it is fine, but if i ran it outside the armrest i would probably return it. it would drive me crazy disconnecting and reconnecting. It wasnt too expensive which is good, but i wish it were more reliable. would probably look for a different brand next time.