DIN 1480 Marine Grade Heavy Duty Hot Galvanized OC Open Body Hook Eye Turnbuckle Drop Forged

Whenever you need to gradually adjust the slack within a tensioning assembly, these handy rigging devices will be used. Also known as bottlescrews, the threaded metal couplings are used to connect and increase or decrease the length of ropes, tie rods, cable lines, and so on.

As with other fasteners, turnbuckles come in different variations in length, size, type, and configuration - each suitable for specific uses. There are three parts that make up a typical turnbuckle:

One rectangular body that has holes on either end – one side with right hand internal threads and the other with left hand internal threads.
Body sizes range in length from about two inches to over 12 inches. However, turnbuckles are measured by the length of their “window”, or take-up inside the body, rather than their entire length.
Two threaded inserts, or end fittings, that have either a hook, a clevis jaw, or an eye at the non-threaded side. A hook end fitting is self-explanatory, while an eye end fitting is a closed hook. The opening of a jaw end fitting is secured by a bolt, nut and/or pin system.
The thread diameter is an indication of the size, and therefore load-bearing capacity, of the threaded part of the inserts.
Instances where turnbuckles are used dictate that they must be able to withstand high forces without breaking. For that reason, most turnbuckles are made of galvanized or stainless steel. The type you choose will be determined by the factors that are most important to your assembly:

Galvanized steel turnbuckles are the cheaper of the two materials. Although they can be used outdoors, they are not nearly as corrosion resistant as their stainless steel counterparts.
Stainless steel turnbuckles are extremely resistant to rust and other forms of corrosion. This higher level of corrosion protection makes them a superior choice for outdoor applications and high moisture, high chloride, and saltwater environments. Bear in mind that demanding marine and coastal conditions require high-quality 316 grade stainless steel for safe and prolonged use.