2.5mm universal pen , detachable, easy to replace the pen core. Model: B3S30 Output Power: 30mW operating hours: 5h Interface: 2.5mm Output wavelength: 650nm Battery: B3S30: 5V, 900mAh Colour:black Material:plastic Size:125 x 35 x 17mm Package Contents: 1 x Fiber Optic Tester Pen 1 x USB Cable 1 x Ceramic core Only the above package content, other products are not included. Note: Light 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. Longer penetration distance, stable performance and long service life. With LED light for easy operation in dark environment. 3 levels of brightness are adjustable, and there is a power signal light, pay attention to the power at any time. and portable, easy to carry and comfortable to hold. It is used to detect optical fiber breakpoints, for the construction and maintenance of integrated wiring, the production and research of optical components, and other optical fiber projects.