It belongs to UR type wire conductors butt splice, which changed complicated traditional cable wire twist and soldering connection . Insert three conductors separately into three ports without stripping conductors insulation; Crimp or squeeze the yellow button onto the inside three conductors with a pliers (here is not included.); Now you finished it! Gel-filled inside design promises an air-tight environment for conductors. Good quality and exquisitely design offer corrosion-resistant function to protect the connection against air and moisture. Product Name : UR Connector Model : Type : 3 Port, Single Blade; Applicability : To Connect two Telephone Wires, Data Signal Cables, and Other Conductors. Suitable Wire Conductor Diameter : 0.4mm-0.9mm Material : Plastic Casing, Gel-Filled Inside Main Color : Clear, Red Size (Each One) : 19 x 12 x 8.4mm / 0.7" x 0.5" x 0.33" (L*W*H) Total Weight : 53g Package Content : 55 x UR Butt Splice Connector Note:Light and different displays may cause the color of the item in the picture a little different from the real thing.The measurement allowed error is +/-1-3 cm.