I bought a second tube to make a 11 inch hammer for looser pins. I currently use this with the rosewood handle, but ordered another carbon tube handle to use instead, since the looser pins require less force hence less stress on the hand. I also like the advantage of the subsequent reduction in weight. I use this with the 15 degree head. It is used primarily on vertical pianos.
Enter the Fujan hammer.
A few years ago I tried the original Fujan hammer of which the main component was an aluminum tube. I found its large diameter to be quite uncomfortable to use. Steve Fujan had a 30 day return policy on that hammer, so I returned it. When I read about his new hammer using a carbon fiber tube I was very interested. When I found out that the diameter of the new hammer was the same as most standard levers I immediately ordered one.

I was initially taken aback by how light it is. It is almost freakishly light considering its size. When I put it to the test tuning some pianos with pins so tight they make a bang when they finally move, I was amazed how much control I had over those stubborn pins. The Fujan hammer is 13 inches long but incredibly stiff. It is a very different experience tuning with this hammer. I can not discern any flex at all. I gather from Fujan's website the carbon tube is suposedly 25 times stiffer than a steel rod the approximate diameter of a standard tuning lever shaft. The joint where the head threads onto the shaft is almost the same diameter as the tube itself, with fine threads and a solid mate between the two when tightened, so flex at this joint is minimal.

I have incorporated the Fujan hammer in my everyday tuning and would like to share some observations I have made.

The hammer, with its rounded rosewood handle is fantastic on very tight pins, but I found it somewhat more challenging to tune a piano with average pin tightness. I finally attributed this to the added weight of the rosewood at the end of that 13 inch lever. I primarily employ the jerk method of pin manipulation and this extra weight adds a degree of difficulty to the control of small pin movements. I think this handle would be fine for tuners that tune with a smooth motion.
I subsequently ordered the straight handle from Fujan, which is the same diameter and made of the same carbon fiber as the tube of the hammer. It weighs 48 grams as opposed to the 83 gram rosewood handle. Using this handle made an amazing difference. I use the hammer all the time now, not just for pianos with tight pins. I do not think a ball end is necessary for a 13 inch lever. Less force is required to move the pin, hence less pressure on your hand. I would, however use the rosewood handle on a 11 inch Fujan hammer for pins on the tight side.
There are four available heads for the Fujan, with 5 to 20 degree angles. I have tried the 5, 10 and 15 degree heads with and without the 5/8 inch tip extension. Using the standard 15 degree head, the hammer will not clear the plate struts on some grand pianos. Using a tip extension on a 15 degree head is not a good idea in my opinion. The 5 degree head, even with the tip extension will also not allow enough plate clearance on some pianos. I find the 10 degree head with the 5/8 inch extension is the best all around combination for clearing tall plate struts. I have yet to run into a piano that, using this combination, will not allow the hammer to clear the struts . As you can see in the photo below, this head-tip combination is quite similar to that of the Watanabe hammer.
15 degree head
10 degree head with tip extension
Fujan next to a Watanabe hammer
It is quite acceptable to remove the handle assembly entirely on the longer tube to reduce the levers length to 11 inches if you need control on a few looser pins. This leaves the threads exposed on the end, but it is still relatively comfortable to use that way for a portion of your tuning.
I believe, speaking as one who uses the jerk style of tuning, the best introduction to the Fujan hammer is the combination of the basic 9 3/8 tube which makes a 13 inch lever, a 10 degree head with the 5/8 inch tip extension, and straight handle assembly. If you need a shorter lever now and then, you can remove the handle and just use the tube alone. I initially wrapped a piece of adhesive fuzzy velcro around the threads for additional comfort when tuning without the handle, but I no longer find it necessary.

I hope someone out there will find these observations helpful. If someone does the math regarding how much money I spent coming to these conclusions, please do not tell me :)

I'd like to mention that Steve Fujan was helpful in allowing me to return the 5 degree head in exchange for a straight handle.

The Fujan is an expensive tuning lever, but it is worth every penny! It is a unique concept, but the 30 day money back guarantee certainly helps alleviate any apprehension you may have about its purchase. I am sure once you give it a try, the thought of returning it will not even enter your mind.

Michael Musial RPT
I am now in my 4th decade of tuning pianos. I could not estimate how many pianos I have tuned in my career, but I know it is a heck of a lot. I would not want to guess how many months of my life in total up to this point have been spent sitting/standing before a piano with a tuning hammer in my hand. Considering that the tuning hammer is the main tool of my profession, I believe I should be using the best one available to make my work effecient, enjoyable and as easy on my joints and muscles as possible.

For decades I have been on a search for the perfect tuning hammer. I have been mainly frustrated by the flex in traditional tuning hammers. The shafts flex slightly when force is applied and there is flex where the shaft threads into the tuning head. I've had a shaft break at these threads, fatigued after years of flexing at that point.

After trying many different hammers I finally discovered the Jahn hammer which eliminates the "L" joint where shaft and head meet. I have used the Jahn lightweight hammer for years now. It has been my favorite hammer because of its stiffness and light weight.

I do some floor tuning for a couple of stores and am sometimes faced with a day of tuning many Chinese pianos with incredibly tight tuning pins. This can really take a toll on my tuning shoulder. I needed a longer hammer for better leverage with which to tackle these pianos. I tried using a Jahn extension hammer, moved out to be 13 inches long. The shaft flexes noticibly when extended that far, and the extension hammer is quite heavy.