18''- 22 base-square groove 1. For casement window 2. Made in ss 304, ss 201 3. Square groove, two- pivots pointed, straight arm or curve- surfaced arm 4. Biggest open angle 90 5. After 50, 000 times opening tests 6. Specification: 4 arms, length 18 base width 22mm, arm thickness 3.0mm. 100 pieces per box, export cardboard packing