Made of high-strength aluminum alloy for greater durability, can be used for long term. Suitable for both indoor and outdoor structural applications including garden sheds and fencing. Ideal for forming perpendicular joints in fence railings, greenhouse frames, shed supports or furniture structures. Start: Slide the square tube into the joint and secure it with screws. Smooth interior fit ensures a firm, balanced grip on all three outlets of your tube frame or furniture project. Great connectors for building lightweight shelving, pet enclosures, chair frames, partition brackets or chain link fence structures.