A Security Defender stay is a device that is used to hold open a window or door. It is typically installed on the side of the window or door, and is designed to be adjustable so that the amount of friction can be adjusted to suit the weight and size of the opening. The stay may be used to prevent unauthorized access or to limit the movement of the opening to a certain range. It may also be used to prevent damage to the equipment or to ensure the safety of operators and other personnel. The size of the stay, in this case 500mm, refers to the length of the stay, and the model number A046 may be used to identify the specific type of stay being used. 13mm may refer to the strength or durability of the stay, and Coastal may refer to the location or environment in which the stay is intended to be used. It is important to follow the manufacturer's instructions for the proper use and maintenance of the stay, as well as any safety precautions that may be necessary when working with the equipment.