Prime-Line Products PL 7721 Screen Frame Corner, 3/8-Inch X 3/4-Inch, Gray Plastic,(Pack of 4) Plastic Corners are used to assemble 3/8 thick window screen frames Square-cut installation for fast and easy construction Gray Vinyl Construction Durable Plastic Material Plastic Corners are used to assemble 3/8 thick window screen frames Gray Vinyl Construction Durable Plastic Material