These would work. Sorry there's no size reference
Female connector
Amazon.com: American Terminal E-FFR250N-100 22/18-Gauge Economy Nylon Fully-Insulated Female Quick Disconnects: Car Electronics

Relay
Amazon.com: Install Bay Tyco Relay 12 Volt 30 Amp Each -E-123: Electronics

Nice relay connector, instead of the female piece connectors, you could get this one piece unit.
Amazon.com: 12 VDC 5-PIN RELAY SOCKET: Electronics