TACHOMETER DT-2236 Photo Contact Digital Tachometer. From Lutron this one instrument combines both a Photo Tachometer ( RPM ) and a Contact Tachometer ( RPM, m/ min., ft/ min. ) . Features Wide measuring range : 0.5 to 100, 000 RPM. 1, 000 RPM, 0.1 RPM resolution . High precision with 0.05% accuracy. Memorize the last value, max., value, min. value High visible LCD display. Exclusive one chip LSI circuit & crystal time base The use of durable, long lasting components, including a strong, light weight ABS plastic housing, assures almost maintenance free performance for many years.