Ultra Parking Blocks are specially engineered and channeled for added strength while remaining super lightweight and easily manageable by a single person. Our 3 1/4" Ultras and 4" Ultras are injection molded from 100% recycled plastic. Ultra Parking Blocks stand the test of time installed in extreme weather conditions, making them ideal for both hot and cold climates. Our Ultra Parking Blocks are perfect for business parking lots, apartment rental complexes, and large commercial parking lots. Made in the USA.