Shipped in 16 pieces / set standard is 8 red and 8 green Everyones goto crash and burn prop multicopter counter-rotating propeller. The Gemfan is known to take lots of abuse and bounce right back, just bend them straight and carry on. They come in various colors so you are welcome to pick and choose if you want. For the more advance flyers, some of the harder higher pitch props would be more appropriate, but if you are starting out, or just crash as much as I do, have lots of these on hand, you will need them. Remember, there is nothing worse than being short a prop at the beginning of a flying day. Ouch! As in both marine and commercial aircraft, the red is on the left and the green is on the right. Some people mount the colors different back and front, but left and right is actually the industry standard.