• T-Hinge: This refers to the shape of the hinge. It has a long "strap" or "arm" that is attached to the door, and a shorter, perpendicular leaf that is attached to the frame or post. When installed, it looks like the letter "T". This design is beneficial because it distributes the weight of a heavy door across a wider area, preventing sagging.
• Heavy Duty: This indicates that the hinge is built to withstand significant weight and stress. The material is typically thicker and stronger than standard hinges. "Heavy duty" hinges are designed for larger and heavier gates and doors, often with weight ratings specified by the manufacturer (e.g., capable of holding a 20kg or 30kg door).
  
• Black: This describes the finish of the hinge. The hinges are often coated in a "black japan" or a black powder-coated finish. This coating provides a sleek, traditional aesthetic and also helps to protect the metal from rust and corrosion, making them suitable for outdoor use.
• 2 Piece Pair: The hinges are sold in a set of two, which is the standard number needed to hang one door or gate.

In summary, a Heavy Duty Black T-Hinge (2 Piece Pair) is a robust and durable hinge designed for heavy doors and gates. Its T-shape provides strong support, while its black finish offers both corrosion resistance and a classic, decorative look.