The Speedmeter is used on golf courses for measuring speeds of golf greens. It is an instrument that compares with respect to the speed of other greens under the same conditions. It is very similar to the USGA's Stimpmeter, as it accurately, objectively and statistically measures a putting surface's speed, providing you with the stimp reading of the golf green.
The green's speed depends on many factors such as slope, type of grass, irrigation, weather, time of day and more. That is why the speed of a green that measures equally but are at different courses is different. Thus, measuring a greens speed accurately can only be measured under the same exact conditions – the same course, time, and grass type.