This is a set screw lock collar. It is for a 0.50 or 1/2 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.
With it's wide hub and finished bore, this ten teeth steel roller chain sprocket is ready to mount to a shaft.
This is set screw lock collar. It is for a 0.375 or 3/8 inch shaft. They are steel and zinc coated.
SparkFun's minimal design approach to Arduino. This is a 5V Arduino running the 16MHz bootloader.
900 MHz 3 dBi Rubber Duck Antenna - SMA Male Connector