One to display cumulative time at present, the other to display alarm value you set. The time can be used for time cumulation and countdown. Also can be used to control equipment aging test automatically. The time unit is settable: hour, minute or second. With start/pause control, convenient to use. With only one alarm: RELAY. Display: 4 Digits Display Consumption: Less than or equal 3VA Range: 0.01s-9999H Output: RELAY Accuracy: +/-0.01%F.S Reset Time: Less than 0.2s Delay Time Range: 0.01s-99.9H Power Supply: 90-260V AC/DC Item Size: 4.8 * 4.8 * 8.5cm / 1.9 * 1.9 * 3.3in Item Weight: 103g / 3.7oz color: Shown in FIG. Material: Plastic Package Content: 1 * Timer 2 * Bracket 1 * User Manual(English) Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.