The raw materials: the rail parts, connecting rod and rivets: 430 stainless steel. Hardware Tip: zinc alloy. Plastic parts: Nylon 6. Data evaluation: Function: cycle test over 25,000 times, in line with BS 6375 PT.1: 2004 & PT 2:1987 standard. Corrosion resistance: comply with BS EN1670: 1998 Level 4 standard. Open angle: 16 inches in line with BS 5588:1998 PT1: 1990. Building codes B, all comply with BS 8213 PT1: 1991. Features: flat open 12-and 16-inch easy to clean and 90 degrees window stay. Raw materials used in high grade stainless steel 430. The opening angle of 90 degrees, easy to use. Release the button, you can easily find open clean. Window support total stacked 13MM.