It does not require heating by flaming nor special tools. Pull out the plastic string from silicon rubber tube, the silicon rubber will tightly shrink on the need position. Reliable, superior insulation & high-recovery elasticity; we have adopted special silicon rubber, which will keep its radial pressure permanently ensuring environmental & electrical protection. Superior hermetic sealing; for cable splicing, we have adopted triple hermetic sealing technology & silicon rubber with hermetic & hydrophobic performance; there will be no serious fault due to environmental cause.