Pixnor 100pcs Insulated Heat Shrink Butt Wire Electrical Crimp Terminal Connector 1.5-2.5mm Color: mainly blue. Material: durable copper, PVC and tinplate. Suits cablewire size: 1.5-2.5mm. Standard crimp and then seal heat shrink butt connectors. Guaranteed to hold the strong crimps. Dual-walled design, polyolefin tubing in outside and hot melt adhesive in inside.