The Delta cleats are for older Look pedals. Shimano licensed the Look design and used it for a while before they transitioned to their now-standard SPD-SL.

Shimano "Look" Compatible Pedals - Bicycle Parts at discount prices / the Buyer's Guide / Bicycle Parts at their finest! / Professional Bicycle Source / Bike Pro

Lots of people still run the older Look and Shimano pedals so they still sell the Delta cleats.