The Easy-Twist WC-A-25R 25-Count Bag of an assortment of Blue (22-14 AWG), Grey (22-14 AWG), Orange (22-14 AWG), Red (22-10 AWG) and Yellow (22-8 AWG) Standard-Style Wire Connectors are designed for use on copper wires. They’re made of flame-retardant thermoplastic rated for a maximum temperature of 105˚ Celsius (221˚ Fahrenheit). The quick-grip square spring design grips in fewer twists and can dead-end a single wire, while the ergonomic ribbed texture makes them easy to twist. Their compact design is useful for applications in tight areas or anywhere else you need to connect wires.