You are purchasing 2 units of the constant current power driver for laser diodes. Works with AixiZ and other standard laser diodes. Driver Size :10*20mm TTL modulation 0-5VDC <5kHz 0V off @ >2.5V laser on Current :80-400mA As shipped with 5R6(5.6ohm resistors) High Range ~450ma max Vcc---------Voltage Out () Max Output (1mv = 1ma) 3VDC----------2.9VDC-----------27ma 3.5VDC--------3.1VDC-----------76ma 4.0VDC--------3.3VDC----------144ma 4.5VDC--------3.5VDC----------226ma 5.0VDC--------3.6VDC----------310ma 5.5VDC--------3.6VDC----------400ma 6.0VDC--------3.75VDC---------430ma If the resistors are changed to 10ohm for the Low Range: ~250ma max 10 ohm resistors(Low Range): Vcc---------Voltage Out () Max Output (1mv = 1ma) 3.0VDC---------2.88VDC--------22ma 3.5VDC---------3.12VDC--------54ma 4.0VDC---------3.17VDC--------79ma 4.5VDC---------3.24VDC-------150ma 5.0VDC---------3.39VDC-------222ma 5.5VDC---------3.39VDC-------243ma 6.0VDC---------3.40VDC-------243ma Note: TTL must be provided with 2 - 6VDC to operate. A 1N4**** or any SMD power diode can be connected to Vcc"+" and the cathode(banded end to TTL"+") to eliminate seperate power supplies being needed for operation.