Features: These external brackets are made of metal material and are rugged and reliable. They connecte two square aluminum beams at a 90 degree angle. Use in pair to obtain the optimal strength. Need fast rivets and pegs or thumb screws and wing nuts (not included). 8mm hole distance, 8.1mm big hole diameter, 3.8mm small hole diameter, compatible with for TETRIX PRIME. Specification: Condition: Brand New Item Type: 90 Degree Beam Bracket Material: Metal Quantity: 5pcs Item Size: 48x48x6mm / 1.9x1.9x0.2in Package List: 5 x 90 Degree Beam Bracket