Square Pipe Connector/ Square Tube Clamp Connector/ 304 Stainless Steel Hardware for 28mm Square Pipe/ Glass Fixing Rod - Walmart.com
Amazon.com: CONNECTOR RIGHT ANGLE FOR SQUARE TUBE JOINT 2 WAY PIPE PROFILE PLASTIC 20MM 25MM 30MM 20x20 25x25 30x30 (A=20 x L=36 x L1=36 x t=1.5) : Industrial & Scientific
430003 | Square tube connectors - with adjustable angle technopolymer, STC-A Type | ELESA | MISUMI