The tubes are used to protect and insulate the fiber optic connectors and splices. The heat shrink tubes features: Cross-linked polyolefin and hot fusion material with a stainless. A Fiber Optic Splice Sleeve is a protective tube designed to encase a fusion splice—the point where two optical fibers are joined together. After two fibers are precisely fused using a fusion splicer, the splice is fragile and needs protection from physical stress, moisture, dust, and other. In general, fiber splice protective sleeves are made of cross-linked polyolefins, shrink tubes from heating, hot and melted tubes, and single stainless steel needles. The easy-to-use design enables fast, efficient work without sacrificing quality.