Channel inset idlers mount down inside a channel frame or vertical mounting surface and bolt horizontally. The low profile design is often used on portable equipment where reducing height is critical. Channel inset idlers are available in steel and impact designs. Martin Channel Inset Trougher Idler, C CEMA, 4 in Roll Diameter, 20 deg Trough Angle, 18 in Belt Width, Sealed Ball Bearing, 6.75/5.44 in Roller Length, 23.63 in Distance Between Mounting Holes, 18.51 in Distance Between Roller Ends, Steel