Yes its a Fire Piston. Go to
www.firepistons.com for more info. Jeff Wagner is a good guy to deal with.
I have had mine now for about 10 months (Asian Water Buffalo horn) and it never ceases to bring a smile to my lips when it ignightes first time. I reccomend Jeffs stuff. To those thinking its easier to build one from Home Dept stuff, think again. Unless you can work to 5~10 microns, don't bother.(I measured it with engineers calipers)
You will need a suitable material that is non porous and a lathe. A drill absolutely will not cut it. Just spend the money and enjoy.
Jeff will provide Tinder Fungus, Char cloth and some oakum tinder, along with string for re-wrapping the gasket and a nice pamphlet for care and feeding.
I suggest getting the cheapest finished Cocobolo if funds are tight (I wish I had this, as I think its a more attractive material than the horn)
It works on the same principle as a Diesel engine. There is some technique to it, but anyone that plays sports or used their hands will get an ignition 99% of the time. I took it into work one day and the dweebs couldn't ger it right lol
Place a little tinder in the recess that is machined into the end of the piston. Push it into the cylinder so the gasket is just in. Either push the piston down firmly and fast and extract very quickly as there is no air in there anymore and the little ember needs to breath, or ram the cylinder and piston towards each other for greater compression. Tinder fungus works the best, hands down. Char cloth is good too with a very high sucess rate, but if you shred some 0000 steel wool with the Charcloth its very easy to extract it after ignition (the Charcloth on its own is very frail and somewhat a pain in the rump to extract after ignition)
I have a design for a machine to make pellets of Charcloth and 0000 wool the same size of the recess on the piston but haven't got around to making it yet
Its truly belong in the realm of Gadget but it is still worth mention in the Gadgets and Gear section.