PowerPole connectors (formerly known as Sermos connectors) from Anderson Power Products have been very popular with electric airplanes and sailplanes. They were the first low-resistance connectors - made of silver-plated copper. The secret of their success is the stainless steel leaf spring built into the plastic housing. This spring applies 25 lb of pressure onto the contacts, ensuring good, vibration-proof contact. Contact resistance has been measured at 600 micro-ohms. PowerPole connectors are very easy to use , compact, will handle moderate current, and are insulated but not polarized unless you slide them together in pairs. If you slide them together you can use the roll pins to lock the 2 connectors together. These are 30 Amp connectors, suitable for wiring up to 12ga. This item includes: 10 black plastic housings, 10 red plastic housings,20 silver plated copper connectors and 10 roll pins.