These zinc plated carbon steel bolt clamps are used for spiral hoses and designed specifically for PVC suction hoses with a spiral helix where traditional flat banding clamps do not seal well.
To determine which style clamp is needed for your hose look at the end of the hose; if the helix spirals in a clockwise direction away from you (along the hose), a clockwise clamp is needed. If the helix spirals in a counterclockwise direction away from you, a counterclockwise clamp is needed.