General description Polished finish quality open body turnbuckles, commonly known as rigging screws, straining screws, and barrel strainers. Technical specifications D1 (mm): 12 L (mm): 200 L1 (mm): 310 D (mm): 18 Material: A4 grade stainless steel (T316 S31) Other information This material offers greater corrosion resistance than A2 in certain environments and is often used for marine applications, especially when in direct contact with salt water.