So i decided to amplify my Martin Dreadnaught (a really, really nice acoustic guitar). I didn't want to spend a lot if it just wouldn't sound good with a pickup, and saw this had consistently good ratings. I can't speak for other acoustic pickups, but this far exceeded my expectations, and I don't plan on buying a more expensive piezo, or soundhole pickup.

ATTACHING IT
Unfortunately the narrow portion of the barrel is not long enough to fit through the end/tail block; and I didn't want to drill a new hole in my not-so-cheap guitar just to test out a relatively cheap pickup.

So I attached the pickup in the regular position inside the body behind the bridge, and just ran the cable out from the sound hole. The jack is held onto the pickguard with some scotch outdoor mounting tape (which is kind of like really strong gum, it can be removed without leaving sticky residue); which holds it in place well enough to plug in a cable and move around as long as I don't jerk the guitar quickly.

SOUND QUALITY
I plugged it into my cheap, regular guitar amp, and whoa! The package mentions two locations you can place the pickup, and because I needed to run it through the sound hole, I could only place it where more treble is picked up. So I have to compensate on my amp by turning down the treble to 7 or lower

Because the pickup is a transducer, no electrical feedback/interference is picked up, so the sound will be very clear and crisp. It would probably sound even better on an amp with better electric shielding; the only noise I get even at max gain, max input volume, is from the amp itself, heard with every instrument I plug into it if I turn the master volume up too high.

Another thing to consider is that transducers pickup vibrations, so it won't pick up sound when placed a millimeter away from the guitar body, but will when touching it. So with that in mind, the pickup will strongly output every sound you make to the guitar body; like it brushing up against your body, a zipper hitting the guitar, your fingers sliding on the strings etc.

I agree with all the positives that have been written and I give it 5 stars but all should know that this rating is relative to price and I have no experience with high end stuff. I put mine in a sturdy little $100 Johnson travel guitar that I always liked the feel of but sounded not much better than an unamplified electric guitar. This little $14 unit kept me from buying the sweeter, louder, sounding $200 Martin Travel guitar (sweeter but less sturdy and rough and ready). In any case, I have a fine little beater guitar now that sounds great! And I bought a second one for my little $60 Kala Uke. (And of course I am now going to have to get a Pignose portable- so it is slippery sloop.) So here is the true purpose of my review. The way I installed this thing was to google "install endpin jack" This takes you to the following YouTube video: [...]This guy knows what he is doing and I followed his directions because the product packaging gives you no guidance at all. If you do no have the right size bit, borrow or buy one do not improvise too much. I did use a rat tail file to open the hole a bit. I would suggest that you not fit the thing in too tightly because you have to allow room for the wood to contract in dry weather! So to the person who put this gadget into a more expensive instrument, I would make darn sure that the hole is big enough and then watch it in dry weather to see that no cracks start to develop in the finish.

I was considering a $100 K&K pickup to amplify a $40 pawn shop guitar I have grown fond of, I bought it to take to the beach and camping, places where I would be too nervouse to bring my expensive guitar. I couldnt justify spending over double for a pickup than I did for the guitar so I bought this and am glad I did. Arrived in one day, and I first experimented with different placements using the double sided adhesive that came with it on the outside of the guitar, plugged my cord into it un-installed and played around for 20 minutes, you'll notice a huge difference in sound from inch to inch. Found a sweet spot near area "2" on the weak instructions. I drilled my hole using a straigh bit because my end pin was screwed into a mahoghany block almost 1" thick, I didnt want a tapered hole from a reamer, I wated a straight hole. As others have noted, it was impossible to fit my arm through the soundhole, so I inserted a philips screwdriver through the end pin hole, and slid the jack onto the tip of the screwdriver to help guide it out through the hole after first slipping on the plain washer and then the friction washer with the little teeth to dig into the wood and hold. Because you cant reach in there and hold the jack steady while tightening the outer nuts, they give you holes through the threaded jack (very easy to go un-noticed) I was able to spin the washer and nut on the threaded end, and secure them by holding the threaded portion from spinning with an ice pick or awlinsde the jack through one of the small holes while I tightened the nut firmly. Took 3 trys before I had it adjusted to the perfect length so that when I spun the nice little finishing cap on over the threads, it tightened down just right with the threaded portion flush with the cap for a neat appearance. Too much and it sticks out, too little and theres not enough thread to tighten this cap on, you adjust the length of the installed jack with the nut on the inside of the guitar, theres plenty of threaded jack there to accomodate any thickness of the block of wood at the tail of the guitar where the 2 sides meet. Plugged into my fender acoustasonic 30 and Wow was blown away by the sweet sound, I am so glad I saved a ton of money! Ordered 2 more for my other guitars, Even one for my nylon stringed acoustic since the pickup is not magnetic. I will say this the output is very low, nessesitating that I turn up my amp to almost 10 to fill my livingroom, this would not work for playing out without a preamp, but I like that theres no battery, and I plan to buy a strap mounted external preamp that I can economize and use one preamp for my 4 guitars rather then installing 4 preamp equipped pickups in all my guitars at $100+ each! Terrific bargain for the price!!!

This transducer works well. I installed it in my guitar, adhering it underneath the bridge and this can be a bit tricky. Overall I'm very happy with the sound- works well and is a great value for the price

I have a lot of guitars and do all the work on them myself.
A couple of secrets to installing the mike pickup:

After you drill the hole, and are trying to figure out just how to get the
jack into place from the inside of the guitar, do this;
Get a guitar/patch cable and run it through the hole you just drilled until you can grab it through
the sound hole. jack into the AXL and then pull it out the hole using your cable. You may have to do
this a couple of times to get the jam nuts set for the right depth, so having a way to make this process
easier is a big help. Also, I did not use the giant endpin collar that came with the assy, as it just takes
up a lot of thread space to accomplish nothing.

Finding a sweet spot on smaller guitars/ukulele/mandolin's can be close to impossible because the sound
hole is actually so small, you can't get your hand in, and finger length is as far as you can go, so in most cases, go in the direction of the low E string side as this is what is typically lacking on the smaller instruments unless you have Jimi Hendrix hands and in that case, congratulations.

Finally, on Travel guitars; GET RID OF THE GIANT STRINGS THAT COME ON SOME OF THESE THINGS!
My SX traveller came in with 11-54's and I could not even hear the low E string. I had an old set of electric 10-46's I took off of a BB King Lucille, and just for the heck of it swapped them out; Man what a difference; actually so much difference that I really didn't need the AXL I just installed even though it's a fun addition.

As far as an amp, I have a little HoneyTone that has been feeling out of place alongside my very large amp arsenal, and just may have found a home, as it is about as small as you can get to go along with the Travel guitar.