The CableMaster FO is a multi-functional, pocket-sized optical power meter with a visual fault locator (VFL) designed for testing and troubleshooting fiber optic networks. It includes features such as power and attenuation measurement for 7 different wavelengths, a VFL for port/polarity detection, an RJ45 patch cord tester for wiremap, and a flashlight. The device has a rechargeable battery that lasts up to 80 hours and can store 50 measurement results. It is ideal for verifying FTTx installations, measuring power at fiber optic interfaces, determining attenuation on fiber optic cabling, and checking for interruptions using the VFL.