No.9 (4.5mm) Pozi Raised Head Countersunk Wood Screws DIN 7995 A2 Stainless

No.9 (4.5mm) pozi raised head countersunk wood screws to DIN 7995, in A2 stainless steel. The countersunk underside beds into the wood, a low dome finishes just above the surface, and the pozi recess takes a PZ2 bit.

Being A2 stainless, they cope with outdoor work such as cladding and garden projects just as well as indoor joinery. There's no minimum order, so you can buy exactly the number you need, and the price per screw comes down as the quantity goes up.

Where pozi raised head screws are used

Pozi raised head screws suit fixings that stay on show, where a domed head looks tidier than a flat one. They're a common choice for door and window furniture, hinges and cabinet hardware. A power driver tends to slip out of a slot, but the pozi recess holds the bit well, so these drive cleanly with a drill driver.

They're part threaded, with a plain shank below the head. Put a clearance hole through the top board and the thread bites only in the lower one, drawing the two together.

The underside of the head is a 90° cone and fits a standard 90° countersink bit, leaving just the dome above the surface.

Finding the right size

The higher the gauge, the thicker the screw. A No.9 has a 4.5mm thread, and sits between the No.8 (4mm) and the No.10 (5mm).

On a raised head screw, length runs from the point up to the rim of the countersunk part, level with the surface. The dome sits above the wood, so it isn't included. There are 11 No.9 lengths, from 25mm to 100mm.

The thread's nominal size is 4.5mm, so a caliper on a new No.9 shows 4.5mm or just below. Under the head, the plain shank is allowed to be thinner, as small as 4.02mm. Both measurements are listed in the dimensions table.

Stainless grade

A2 is the common stainless for fixings, in the same family as 304 and 18/8. It's the usual choice for outdoor timber because it stands up to rain and damp. It's close to non-magnetic, and a slight pull on a magnet is nothing to worry about.

Near the sea or a swimming pool, salt is harder on stainless, and A4 is the better pick. Our A2 stainless steel and A4 stainless steel guides explain why.

Questions about these screws

What size is a No.9 screw in mm?

A No.9 measures 4.5mm across the thread. These are made to DIN 7995, which also sets the head: 8.3mm across, 2.35mm at most from the underside to the rim, a dome of about 1.1mm on top, and a PZ2 pozi recess.

The No.9 name is borrowed from imperial sizing. These screws are metric, and the 4.5mm thread is the nearest metric size to an imperial No.9, at roughly 4.5mm.

Which bit fits a No.9 pozi raised head screw?

You need a PZ2 pozi bit. A pozi head looks like a Phillips head, but it has four small tick marks between the arms of the cross, and the bit has ribs that line up with them.

A Phillips bit will turn it, but it doesn't seat fully and tends to slip out as the screw tightens, which can damage the head. Matched to the right bit, the pozi recess takes more turning force before the bit slips.

What is a No.9 x 2 inch screw in mm?

That's 4.5 x 50mm in metric. Inches are still common for wood screws, so you'll see both on every length, for example 1in (25mm), 2in (50mm) and 4in (100mm). The length itself is metric and the inch figure is the closest equivalent, so a 2in screw here is 50mm rather than 50.8mm.

How do you measure a No.9 pozi raised head screw?

A caliper across the outside of the thread gives the size. On a new No.9, expect 4.5mm or a fraction under, because 4.5mm is the nominal size. The plain shank under the head is a separate figure, and DIN 7995 allows it to be as thin as 4.02mm.

Measure the length from the tip to the rim of the countersunk part, where it meets the surface, and leave the dome out.