This is a pair of two DuBro 3" Super Slim Lite Wheels, designed for most ARF's that need larger diameter treaded wheels to taxi and take-off from grass fields. They are slim to fit onto short and small diameter axles.
The axle hole is (3.0 mm) 0.118" dia. and a width of (16.4 mm) 0.645". They are lightweight at 8.8 grams/ea for the 275SSL and 10.2 grams/ea for the 300SSL. These also have many more applications in school projects and various crafts.