Referee Cards - Red and Yellow - Durable and Visible - Ideal for Soccer and Other Sports** Do you want to officiate games like a pro? Do you need a set of referee cards that are easy to use and show? If so, you need the Referee Cards by SportMaster. The Referee Cards are a must-have accessory for any referee or coach. The cards are made of sturdy and waterproof plastic that can withstand any weather and impact. The cards are also bright and vivid, making them easy to see and display. The cards come in two colors, red and yellow, to indicate different types of fouls and penalties.