Ultra Parking Block were specially engineered for added strength while remaining super lightweight and easily manageable by a single person. Our goal for the Ultra was to eliminate any previous issues and any foreseeable future issues for parking blocks. Our Ultra is designed to withstand more pressure (over 40,000 lbs of weight capacity) than our previous solid and channeled parking block. This is the BEST Parking Block in the market place today weighing under 20 pounds yet virtually indestructible. 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, our Ultra Parking Blocks are superior to the competition because Plastics R Unique is the original recycled plastic parking block manufacturer.