I have the Fagerstrom "Technopipes". 10" long, 5/8" diameter, with a slight taper. Runs on a single AAA battery. Produces both drone and chanter sounds in your choice of 4 keys, and can be adjusted over a 2 octave range. Also sounds in 3 "voices", Great Highland Pipes, and 2 different smallpipe configurations. Can sound very impressive when plugged into a decent amp. I usually use mine with earbuds. I take it into work, sneak in some practice during down times. They're good to use at home, I can practice at early or late hours without disturbing my Bride. They're great for travelling (although small cylinders full of circuitry tend to give TSA agents a nervous tic). As Auld Argonian said, "Way big fun"