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EnglishZAGO Self-Sealing Fastener Categories: Phillips, Slotted, and Flat Head Options
Updated
ZAGO's site organizes its self-sealing fasteners into four main shop categories: Phillips pan head, Phillips flat head, 100° Phillips flat head, and slotted pan head machine screws. All of them use the company's 360° O-ring sealing technology, so the choice between them comes down to head style, drive type, and how the fastener sits in your assembly—not to whether it seals. Pick a pan head when you want a raised, general-purpose bearing surface, a flat head when the screw must sit flush or countersunk, and a slotted drive when a flat-blade tool is preferred or required.
The four categories at a glance
| Category | Head style | Drive | Typical fit | Choose it when |
|---|---|---|---|---|
| Phillips pan head | Raised, rounded pan | Phillips (cross) | Surface-mounted, general purpose | You need a standard cross-drive and a head that stands above the panel |
| Phillips flat head | Flat, cone-shaped underside | Phillips | Countersunk / flush | The screw head should sit flush with or below the surface |
| 100° Phillips flat head | Flat, 100° cone angle | Phillips | Countersunk, shallow angle | Your hole or panel is cut for a 100° countersink rather than a standard angle |
| Slotted pan head | Raised pan | Slotted (flat blade) | Surface-mounted, general purpose | A flat-blade driver is preferred, or you want a simple single-slot drive |
The site describes the Phillips flat head screws as "designed with a cone shape to fit" a countersunk hole, and the slotted pan head machine screws as "crafted from corrosion-resistant materials, ensuring durability." Those two details are the main selection signals the catalog gives you directly.
How head style changes the decision
Pan head vs. flat head
A pan head sits on top of the mating surface. It gives you a wider bearing area and is the easier choice when the hole is a simple through-hole and head clearance isn't a problem. A flat head is intended to be countersunk so the top of the screw ends up flush with the material—useful on exterior panels, enclosures, or any surface where a protruding head would catch, seal against a gasket, or look unfinished.
Why the 100° flat head is a separate category
The 100° Phillips flat head is listed on its own because countersink angle has to match. A standard flat head and a 100° flat head are not interchangeable if the hole is already cut: if your panel or mating part is machined for a 100° countersink, use the 100° version so the head seats fully. If you're drilling the countersink yourself, match the cutter angle to the screw you buy.
Phillips vs. slotted drive
Both drives are common and both appear here in pan head form. Phillips is self-centering and cam-out is a built-in torque limit; slotted accepts a plain flat-blade driver and is simple to clean and inspect. The practical rule: choose the drive your assembly tools and service procedures already use, since the sealing performance comes from the O-ring, not the drive.
Selection considerations beyond the head
- Corrosion resistance. The site explicitly calls out corrosion-resistant materials for the slotted pan head line. If the joint sees moisture, washdown, or outdoor exposure, confirm the material and finish for the specific part rather than assuming it carries across all four categories.
- Sealing mechanism is shared. Every category is presented under the same 360° O-ring technology, described as providing "leak-proof sealing protection." That means the head/drive choice is about fit and tooling; the sealing function is the common baseline.
- Application context. The site lists industries including military & defense, aerospace, electronics & enclosures, offshore wind, medical devices, robotics & drones, marine, energy generation, automotive, LiDAR, industrial manufacturing, and commercial lighting. Use your own environment to narrow material and finish requirements, then pick the head style that fits the joint geometry.
A quick way to decide
- Is the head allowed to protrude? Yes → pan head (Phillips or slotted). No, it must be flush → flat head.
- Is the countersink already cut? If it's 100°, choose the 100° Phillips flat head; otherwise use the standard Phillips flat head and match your cutter to it.
- Which driver does your team use? Cross-drive → Phillips; flat-blade → slotted pan head.
- Does the environment demand corrosion resistance? Check the material/finish on the specific part page before ordering.
For exact dimensions, thread sizes, materials, and availability, use the individual category pages under "Shop our top categories" on selfsealingfasteners.com—the catalog overview gives you the category logic, but part-level specifications live on the product pages.