What Is a Flat Back Stud?

A flat back stud is an earring with a smooth flat disc behind the lobe instead of the little bent-metal butterfly clutch most people grew up with.

That is the whole idea. Everything else about the format follows from it — why you can sleep in one, why it does not catch on a jumper, and why it is the design people wear continuously rather than putting on in the morning and taking off at night.

The anatomy

Three parts.

The post is the bar that passes through your piercing. On these it is 20G — 0.8mm across — which is the standard gauge for a pierced lobe, and the same thickness a piercing studio will have used.

The disc is the flat back itself: a smooth, low plate that sits flush against the skin behind your lobe. Nothing stands proud of the ear. That is the part doing the comfort work.

The fitting is how the two are joined. On a screw back — which is what the LINNY CO range uses — the post is threaded and the disc screws onto it. It is held by a thread, not by grip.

A note on the measurements, because they get quoted wrong

Post length is the number people get confused about, and suppliers do not help.

The standard post here is 7mm. A smaller 5mm post is used across the Lux styles, where the shorter bar suits the design. You will sometimes see "8mm" in supplier material for the same earring — that figure is the total length including the screw threading, not the part that sits in your ear. The number that matters for fit is the shorter one.

The full picture, since it is easy to state precisely: there are 314 screw back styles in the range, and every one of them records both numbers. All 314 are 20G (0.8mm). 301 have a 7mm post and 13 — the Lux styles — have 5mm. The figures for any particular style are on its own product page.

Flat back and screw back are not the same word

These get used interchangeably and they describe different things.

Flat back describes the shape — a smooth disc rather than a protruding clutch.

Screw back describes the mechanism — a threaded post that the back screws onto.

You can have a flat back that pushes on. It gives you the comfort without the security, which for an earring meant to stay in is only half the point. The pieces worth having for continuous wear are both: flat and threaded.

Why the disc matters

A butterfly clutch stands up behind the lobe. Put your head on a pillow for eight hours and it presses into the skin, which is why people wake with a sore ear and a dent and start taking their earrings out at night.

A flat disc has nothing to press. It also has nothing to catch — not on a pillowcase, a hairbrush, a jumper coming off over the head, a helmet strap or a swimming cap.

That is the difference between an earring you are aware of and one you forget about.

Why the thread matters

A butterfly back is held on by friction. Nothing else. It slides on, and it slides off given enough rubbing — which a pillow provides all night and a jumper provides in one motion.

A screw fitting does not rely on friction. It comes off when someone unscrews it and not before.

For a well-healed adult piercing, losing an earring is annoying. For a newer one, it is worse: an empty channel starts shrinking within hours, and the replacement may not go back in the next day. Removing that event is most of the argument for the format.

What they are made of

The post on these is 316L surgical-grade stainless steel — the part that sits inside your piercing, and the part that decides whether your ears react to an earring at all. Gold and silver tones are a plated finish over that same steel rather than a different metal.

Most of the range is also rated waterproof for shower, pool, ocean and sweat, and much of it is made to ASTM F2923-20, the US children's jewelry standard. Both are recorded per style on the product page.

Putting one in

Simpler than it looks, and worth knowing before you are standing at a mirror.

1. Unscrew the disc from the post.
2. Feed the post through from the front, as usual.
3. Hold the front steady and screw the disc on from behind, clockwise.
4. Snug, not clamped. If the lobe is at all swollen, leave a little room rather than pressing the disc into skin.

Then a habit worth keeping: a check by feel once a week. Thumb and finger, a light turn to confirm it is still tight. Ten seconds, and it catches the one that has worked a quarter-turn loose.

Who they suit

Anyone who wants to stop taking earrings out — which in practice means people with sensitive ears, anyone with a second or third piercing, anyone who swims, and children, for whom the screw fitting is doing a safety job as much as a convenience one.

They are less suited to someone who likes changing earrings several times a week. A screw back takes a few seconds longer than a push back, every time, and that is a real trade.

Where to look

Screw back flat back studs is the full range — 314 styles at the time of writing, all on the same fitting. Waterproof flat back studs are the ones rated for the pool and the sea, and kids' hypoallergenic flat back studs are the ones made to the children's standard.

Everything built to be left on sits at hypoallergenic waterproof jewelry, and whether you can really sleep, shower and swim in them answers the question that follows this one.

Questions

What gauge are flat back studs?

20G, which is 0.8mm across — the standard for a pierced lobe and the same gauge most piercing studios use. Every one of the 314 screw back styles here is 20G.

How long is the post?

7mm on 301 of the 314 styles, and 5mm across the 13 Lux styles. If you see 8mm quoted anywhere for the same earring, that is the total length including the threading rather than the part that sits in your ear.

Is a flat back the same as a screw back?

No. Flat back is the shape of the disc; screw back is how it attaches. Some flat backs push on. For an earring you intend to leave in, you want both.

Do flat back studs fall out?

A screw back is held by a thread rather than by friction, so it does not gradually work loose the way a butterfly clutch does. Check it by feel once a week and it will stay put.

Can you sleep in them?

That is what the flat disc is for — there is nothing standing proud of the lobe to press into your ear overnight.

Are they good for sensitive ears?

The post is 316L surgical-grade stainless steel, and the post is the only part inside your piercing. If earrings have bothered you before, a plain steel screw back is the sensible thing to test with, because there is only one variable.