3/8” Split Square Rail Riser can be purchased in black or gray and are sold either individually or in a 10 pack. These spilt square rail risers are used to create better airflow which helps prevent mildew and allows the water to drain off the deck. The lips on the edges of the rail riser help center the spacer on a 1-1/4” wide railing. Rail risers are also known as fence risers.