Check the listing for details. Fiber Optical Tool Sets, 6 Pack 7mm Ceramic Core with Metal Heads. Condition: New. Listed at 10.58 USD. These fiber sleeve core spare ceramic inserts and metal heads are designed for versatile use. They are suitable for most fiber cable testers and red light pens, making them an essential accessory for fiber optic testing and maintenance.Specification:Material: Ceramic Core, MetalTotal Size: 9 x 8mm/ 0.36 x 0.31"(L*D), 7 x 3.6mm / 0.28 x 0.14"(L*D)Package Content: 6 x Ceramic Core, 6 x Metal HeadsAdvantage:Made from quality materials, these inserts and heads are highly durable and resistant to breakage. They ensure a reliable and extended lifespan, allowing for consistent performance during fiber optic operations.Instruction:With improved design and construction, these inserts and heads provide easier installation compared to traditional options. This simplifies the replacement process and reduces the risk of damage or improper connections.