This Zeiss Ikon 5522/5 Micrometer Focusing Deviceis a high-precision, gear-driven mini focusing rail. The base has a 3/8″ inner thread for attachment to tripod or head; there’s a 1/4″ outer thread up top for camera mounting. A few custom attachments are also included: a “stud” type attachment for the base (so it can be held ina clamp) and a short (approximately 2cm) extender for the top. Both are, of course, removable. Cosmetic conditionis good, with some surface wear; function is excellent, and the precision of the gearing is just excellent. Extra bonus: this thing is also tiny- only about 13cm long- and packs easily.