This is a set screw lock collar. It is for a 0.438 or 7/16 inch shaft. They are steel and zinc coated. Perfect for keeping your shafts or bearings in place.
Shaft Collars (sometimes called lock collars) are easy to install; the collar provides an easy way to keep your shaft from sliding or your flanged bearing from coming out.
SparkFun's minimal design approach to Arduino. This is a 5V Arduino running the 16MHz bootloader.
This is a MLT-42-F tracked robot platform and is equipped with flipper arms, 42mm motors, a motor controller, and FLYSKY remote control. This rugged robot platform the treaded robot handles up to 15lbs of additional payload and travels 134ft/min.