PACK OF 8 HEAVY DUTY DOWN RINGS: This set consists of 8 stainless steel D-rings. The rings measure 4.6 x 3.8 cm and are 6 mm thick. They come with mounting brackets. They measure 2 x 5.6 cm and have 6.5 mm diameter holes. The distance between the holes is 3.6 cm. Each set comes with 2 x 2.1 cm screws. HIGH BEARING CAPACITY: Our trailer hitch rings are strong and durable. As they are made of stainless steel, they are rustproof and anti-corrosive. Each trailer hook can support 400 kg of weight and has a center width of 2.6 cm. Each fastener has been galvanized to ensure long-lasting durability. The mounting brackets will anchor the hoop to wood or concrete surfaces. EASY TO INSTALL: Each car tow ring can be easily attached with just two screws. This complete set includes all the screws you need to secure them to your surface. Simply mark where you want to screw, drill your holes and place the bracket and ring in their final position. You can then secure with the screws provided.