The 51mm Air-Flow spinners have a backplate that is 51mm (2 inches) in diameter with an overall length of 46.6mm (1.83 inches). The complete spinner weighs 17.8 grams or 0.74 ounces. 

The Air-Flow Spinners feature a molded plastic spinner cone with a machined aluminum backplate. They are available in 6 different sizes and 5 different colors to fit a wide range of aircraft models. The spinner cones on the 51mm (2-inch) through 75mm (3-inch) sizes are attached to the backplates with a pair of M3 x 6mm socket-head screws, which require a 2.5mm hex wrench to tighten. The largest 82mm (3-1/4") spinners use four of the M3 x 6mm socket-head screws to hold the spinner cone to the backplate.

These spinners are designed to be used with electric motors and feature a set of six angled slots that pump air through the spinner, directly into the motor behind it, to help keep the motor running cool during use. The aluminum backplates have large lightening holes in them to allow cooling air to pass through. These holes also decrease weight and rotational mass of the spinner for quicker motor acceleration. The backplates have a raised knurled area on both sides around the center hole, which provides a firm grip on both the back side of the propeller and on the face of the motor's prop adapter. The spinner backplates have an 8mm mounting hole in the center and comes with a set of plastic reducing adapters so they can also fit onto 6mm, 5mm, 4mm or 3mm motor shafts.

The 51mm Air-Flow spinners have a backplate that is 51mm (2 inches) in diameter with an overall length of 46.6mm (1.83 inches). The complete spinner weighs 17.8 grams or 0.74 ounces.

NOTE: "YELLOW-GOLD-ORANGE" color is like... just think of your childhood mac-n-cheese ;-)