Stable and powerful penetration effect, LASER imported laser head, high thermal conductivity body easily penetrates long distance fiber Note: The laser is harmful, it is strictly forbidden to look directly at the red light. Applicable to a variety of fiber optic interfaces: <2.5mm universal interface FC, ST.SC If you need to detect 1.25mm LC interface, you need to purchase a separate FC-LC adapter Note: Adapters are not standard Aluminum alloy shell, durable and comfortable in the hand, the pen body with metal texture more non-slip Replace the ceramic core by turning the pen counterclockwise and removing the metal tip from the front of the red pen. Note: Ceramic cores are fragile and should not be installed or operated with brute force.