Electronic timing machine, allows instant calibration of most clocks and watches. Photo shows slight error for an 18,000 beat/hr clock (typical for many carriage, alarm and other small clocks), correctable in a minute, vs. waiting hours or days using trial and error. Runs from 9v battery or DC wall-wart (not provided), perfect for the bench or for on-site customer service. Display shows rate in beats/hr, with a number of preselectable rates. Also has "beat" function, helpful in setting hairspring or other means for beat adjustment. An "averaging" function allows averaging over a number of beats (8, for example, for an 8-leaf pinion) to give very stable readings. Beat-amplifier is great for detecting mechanical interference, bouncing and other anomalies. Includes clip-on pickup. This is NOT as capable as the famous Microset timer, but for a fraction of the price, delivers all the basic features needed for day-to-day work. Buyer prepays winning amount plus actual postage costs and insurance. USPS green money orders not accepted - pink (international) ok.