Concrete blocks to prevent vehicle parking on vacant lot left after the destruction of a building. It works like lego to store them. It can also be used to protect events. :
Concrete Parking Blocks — American Eagle Precast Concrete Products
Acton Precast Concrete Limited
Precast-concrete-parking-curbs (Set of 5) - Thrifty Winnipeg -Manitoba's Marketplace
Parking Bumpers, Parking Stops, Parking Blocks in Stock - ULINE.ca
Quality Concrete Parking Curbs | SI Precast Concrete
Parking Curbs | PROFORM
Plastic Parking Block
Parking Blocks Comparison: Concrete vs Recycled Plastic vs Recycled Rubber | G P Roadway Solutions | Honolulu, Hawaii | Lihue, Kauai | Kahului, Maui | Kona, Big Island