The AquaPen AP100 is a portable handheld fluorometer designed for rapid chlorophyll fluorescence analysis and photosynthetic efficiency testing in plant research and environmental monitoring applications. Commonly used in agriculture, plant physiology, and laboratory research, the AP100 provides fast and accurate fluorescence measurements in a compact field-ready design. This unit is cosmetically in very good condition and includes a new USB data cable along with the software licence saved on a USB drive. A water test has been completed successfully with a valid reading displayed, confirming the LED is working correctly. Listed as fully working.