Oval Screw-Lock Snap Hook DIN 5299D, AISI 316 Stainless

The Oval Screw-Lock Snap Hook (DIN 5299D) combines the convenience of a snap hook with the reliability of a locking mechanism. It is made from AISI 316 stainless steel, meaning it’s perfectly suited for marine use and will remain free of rust even in continuous saltwater exposure. The key feature that sets this hook apart is the screw lock collar on the gate. When you close the gate, you can twist the knurled threaded sleeve (collar) until it covers the gate opening. Once tightened, the gate cannot be depressed – effectively converting the hook into a closed loop that won’t accidentally release.

This mechanism is particularly valuable on a boat or industrial setting, where motion, vibration, or an unexpected shift could cause a regular spring hook to open. With the screw lock engaged, you have an added layer of safety. The screw action is smooth and quick; a couple of turns are enough to go from open to locked. The collar is captive (it won’t fall off) and also stainless steel, with ridges for grip even with wet hands.

Size Options & Working Loads:
Our screw-lock snap hooks come in common sizes to match the non-locking versions, but they generally have higher working load limits due to a slightly beefier design:

• 6 mm Screw-Lock: Working load ~0.14 ton (140 kg). At ~60 mm length, this size is perfect for small boat uses where extra security is needed. For example, use a 6 mm screw-lock hook to attach a kill-switch lanyard to your person (so it won’t unclip accidentally), or to secure your portable fuel tank or battery box in place. It’s also great for camping gear – it won’t let your food bag fall from a line overnight.
• 8 mm Screw-Lock: Working load ~0.25 ton (250 kg). The 8 mm size (about 80 mm long) is a versatile choice for mid-sized boats. Use it to connect an anchor rope to a chain thimble securely – the lock prevents any chance of the rope slipping out even if the load fluctuates. You can rely on it for holding deck chairs, attaching dock lines to cleats when you want backup security, or keeping your expensive fishing rods leashed to the boat.
• 10 mm Screw-Lock: Working load ~0.40 ton (400 kg). This robust hook (~100 mm long) suits larger yachts and heavy-duty purposes. Many sailors use a 10 mm locking hook to secure their roller-furling genoa’s tack to the furling drum – it stays put through vibration and heavy winds. It’s also excellent for securing bosun’s chairs (again, as a secondary safety measure) or hanging heavy tools and spare parts in the engine room (the lock ensures they don’t drop). If you use harness lines for rough weather, a 10 mm screw-lock provides confidence that once clipped, it stays clipped.
• 12 mm Screw-Lock: Working load ~0.60 ton (600 kg). Ideal for very heavy-duty requirements on larger vessels or construction sites. Use a 12 mm stainless screw-lock hook to secure a tender boat on deck (tie-down straps with these hooks on ends), fasten cargo nets, or in any critical lashing where you want zero risk of detachment. The high load capacity can handle securing motorized equipment or as part of a lifting sling for non-human cargo (engine lifts, for example, where a quick connect/disconnect is handy but must not open mid-lift).

Safety and Usage: Despite the added security, these hooks still allow relatively quick release – simply unscrew the collar a few turns and press the gate. They are a bit slower to open than non-locking hooks, but that trade-off is usually worth it when safety is a concern. Important: While much more secure, these hooks are still not rated for climbing or lifesaving use in a professional context, because they don’t have the same certified ratings as climbing carabiners. However, they are extremely popular for marine safety applications like securing jacklines, liferaft lashings, safety harness tethers (again, not as the primary life support, but as very secure tether clips), etc. They provide peace of mind that a line will stay attached until you intentionally remove it.

Marine Examples:

• You might use a pair of 8 mm screw-lock hooks to clip your anchor snubber line onto the anchor chain – once locked, they won’t pop off even if the chain jerks.
• Use a 6 mm or 8 mm one to secure the end of your boom tent or canvas cover so that no matter how the boat rocks, the cover’s clips won’t come undone.
• On sailboats, locking carabiners of this sort are often used on running rigging that is semi-permanent – like the downhaul for a spinnaker pole or at the end of a preventer line – where you want easy removal but zero chance of it coming loose during operation.
• Divers often appreciate stainless screw-lock clips to attach gear to their BCDs; they won’t open even if something bumps the gate.

In daily use, just remember to screw the lock closed after clipping on, and check it occasionally if there’s a lot of motion (the vibration-resistant design means it rarely unscrews on its own, but a quick glance is good seamanship). A dab of marine grease on the threads can keep the action smooth over time.

With our Oval Screw-Lock Snap Hooks, you get an excellent combination of quick usability and secure locking. They’ll keep your valuables and important connections safe, with the lasting durability of stainless steel. Whether in a marine setting, industrial environment, or around the home, these hooks are a reliable solution when you need that extra assurance that “hooked” stays hooked.