This manhole cover is made of cast iron through a metal casting process, so it is more durable and stronger than manholes made of cement or concrete. the materials used are: 1. CAST IRON (FC) / Regular Cast Iron The use of this material is used if the load or force that will pass through the manhole or grill is limited to public transportation vehicles such as two-wheeled vehicles, four-wheeled vehicles, and a maximum of ankle trucks because they are only able to withstand light to moderate heavy loads. 2. DUCTILE (FCD) / Cast iron alloy steel. The use of this material is functioned if the load or force that will pass through the manhole or grill is a heavy vehicle such as a double truck, container truck because it can withstand loads of up to tens of tons. 3. STEEL / STEEL The use of this material is used to withstand heavy loads which based on our tests can withstand loads of 50 tons to 70 tons.