The answer is Crimper.
Crimper is a networking device that would allow RJ-45 pins to get attached to UTP(Unshielded Twister Pair), CATs (Category Ns) and STPs (Shielded Twisted Pair) Cables. These are common type of cables used in computer networking. A crimper looks like a pliers only it has narrow ends with a hole where you would put RJ-45 devices together with the cables. In order to make the cable hold on to the RJ-45, the two hands must be squeezed together with an exact force (not too much force). Once the crimper made a sound, that means, your RJ-45 is now locked with the cables inside.
You must be very careful when using this device. Sometimes crimpers has blades that could peel off cables or cut them for alignment and proper attachments. A pair of gloves and googles are also advisable to wear when you use this device for safety measures.