It's hard to imagine, but without heat shrink tubing for fiber optic cables, the luxuries of modern telecommunications might not be possible. Environmental factors and mechanical stress can cause damage and electrical interference, affecting the transmission of data. But, that's not always the best option. Heat shrink tubing offers a clean, semi-permanent way to seal and protect cable assemblies. However, the sealing method used inside these closures largely determines the long-term reliability of the fiber connection. 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.