This is a kit containing 10 pairs of 2-conductor waterproof electrical connectors for use with wiring harnesses. They lock securely together. The are good for wire gauges 20 - 14. They are rated up to 5.9 amps. The proper tool for assembling is a crimping tool. There are several videos about assembly on the Amazon listing. Some on Amazon say they are hard to assemble, they need to watch the videos before trying to assemble them.