These are high quality  Nylon Insulated Butt Splice Connectors (Crimp Terminals) made from solid tubular copper that last a lifetime when properly crimped! 

Seamless Tinned Copper Tube provides a perfect crimp every time!

Angled easy entry funnel ends prevents snags when inserting stranded wire

Centered detent stops wire from being inserted too far

Max Rating: 105°C, 600 Volts

Nylon insulator

Sizes Available:

RED - 22-18AWG - 0.5-1.5mm^2 

BLUE - 16-14AWG - 1.5-2.5mm^2

YELLOW - 12-10AWG - 4-6mm^2