Feature: 1. With LED flashlight button, click to turn on or off the lighting function, can work normally under dark conditions. 2. Anti‑drop silicone cover, detachable protective silicone cover, split design protection is more in place. 3. Exquisite and compact, easy to operate, easy to carry and convenient to store, not easy to lose. 4. There is a continuous wave output with 3 modulation frequencies. Ergonomic design for one‑handed operation. 5. Seven different test wavelengths can be selected, and the selected test wavelength is displayed at the top of the screen. Specification: Item Type: Single Mode Optic Light Source Material: ABS+Silicone Cover Color: As shown in the picture Wavelength (nm): 1310+1550nm (KLS-35-S) Typical Output Power: -5dB Optical Single Mode Connector: SC + 2.5mm universal (LC choose 1.25mm) Power Supply: Alkaline batteries (3 x AA 1.5V batteries)(Not Included) Output Stability: ±0.05dB / 15 minutes; ±0.1 dB / 8 hours Modulation Frequency: CW, 270Hz, 1KHz, 2KHz . Package List: 1 x Single Mode Optic Light Source(Battery Not Included)1 x Accessory1 x Instruction Manual Note: 1. Monitors are not calibrated same, item color displayed in photos may be showing slightly different from the real object. Please take the real one as standard.2. Please note that the new type and old type of this product will be sent randomly, and make sure you will not mind before ordering.