ITEM DESCRIPTION The screw on wire connector features a positive-grip design for easy installation color-coded models cover hundreds of wire combination just strip off the wire and insert securely inside the connector The fixed square-wire spring provides a secure connection that won't relax over time Cone-shaped springs pull wires into the connectors for a firm grip. Features: Applications - Electrical Wire Nuts are great for home theater, speaker wire, stereo wiring, automotive, marine wiring projects, household wiring projects, commercial or residential applications and etc. Assorted Sizes - (10ga-22ga) for various electrical wire gauges, great addition to your electrical connector kit! Wire Cap - No Pre-twisting wire & soldering & tools needed. pull the wires into connector and screw on, spring steel ensure a stable connection when working on wiring projects. They are plastic and they have the expected spring steel little twisty thing in the neck that helps complete a good connection. Screw-On Wire Connector Assortment: Grey, Blue, Orange, Yellow and Red connectors, Perfectly fits for most electrical wiring projects and applications Packaging Content - 40pcs gray wire nuts, 40pcs blue wire cap, 50pcs orange electrical wire connectors, 18pcs yellow Screw-On Wire Connector, 10pcs red wire connection nuts Specifications: Material: PVC, Copper Voltage: Rated at 600V Max Temperature: Rated at 221°F (105°C) maximum 40pcs Grey: 20ga Screw On Wire Connectors 40pcs Blue: 18ga Electric Wire Spring Connectors 50pcs Orange: 16ga Wire Cap 18pcs Yellow: 16ga Cone Connectors 12pcs Red: 12ga Thimble Connectors Storage Case Included: Yes Package Contents: 158pcs Wire Nuts Assortment Storage Case