What the number in the triangle on your lid means

The number in the triangle is a resin identification code. It names the family of plastic the part was molded from, and it was put there to help sorters at recycling plants tell plastics apart by eye.

It has never been a grade or a rating, and most seals and gaskets carry no mark at all.

This guide is for gear you already own. No part Cristel names on the six pieces we sell is plastic, and there's more on that at the end.

Why care what the number means?

In short. It's printed on lids and containers you use every day, and it's easy to read more into it than it says.

You unscrew the lid from your water bottle to wash it and turn it over. Molded into the underside is a small triangle with a 5 in the middle and "PP" under it. The same little mark is on the lid of the soup container in the fridge and inside your kid's lunch box lid.

It's tempting to read that 5 as a score. It names a plastic. It doesn't rank anything, promise your town recycles it, or tell you how the part handles heat or the dishwasher.

What do the seven codes mean?

In short. Each number from 1 to 7 names a family of plastic, and 7 covers everything else.

The code runs from 1 to 7. The letters under the triangle spell out the plastic, and a couple of families go by two abbreviations.

So the 5 on that bottle lid means polypropylene. Bottle caps are one of the standard examples for a 5, which is why it turns up on so many lids.

Where does the code come from?

In short. A plastics industry group introduced it in 1988, at recyclers' urging, and ASTM International now publishes it as standard D7611.

The Society of the Plastics Industry introduced the system in 1988, at the urging of recyclers who needed to sort plastic by type. In 2008 the group handed it to ASTM International, which now publishes it as standard D7611, "Practice for Coding Plastic Manufactured Articles for Resin Identification." The current edition is D7611/D7611M-26.

You'll see two versions of the symbol. The original was three chasing arrows bent into a triangle.

ASTM's revision changed it to a plain equilateral triangle, but molds last for years and plenty of lids still carry the arrows. Both mean the same thing.

Many US states require the code on rigid plastic bottles and containers. A 2022 survey by the plastics trade group counted 36 states with some form of identification rule, and Kentucky's statute, for one, writes all seven codes into its text.

Those rules are aimed at packaging, so a reusable lid carries a code because the maker chose to mold one in. Many don't.

What does a 7 mean?

In short. A 7 is the catch-all: every resin outside the first six, plus parts made from more than one plastic.

Kentucky's statute puts it as "all other resins, including layered plastics of a combination of materials," and the county recycling page we read describes it the same way: everything that isn't one of the first six, plus parts made from more than one plastic.

So a 7 tells you two things. The part is plastic, and it isn't PET, HDPE, PVC, LDPE, PP or PS.

Which plastic it actually is, the number can't say. For that you need the maker's page or an email, and the questions below are written for it.

Is a lower number better?

In short. No. The numbers rank nothing. They're names, in the order they were assigned.

ASTM's text is blunt about the job. The codes "are used solely to identify the plastic resin used in a manufactured article."

A lower or higher number ranks nothing. 1 isn't better than 5, and 7 isn't worse than 2. They're names in the order they were assigned, the way oak and maple are names for wood.

And it says nothing about how the part behaves in your kitchen. Heat limits, dishwasher use, staining, how it holds a smell: none of that is in the number. The maker's care text covers those, or doesn't.

Does the code mean it's recyclable?

In short. No. The standard says the codes "are not 'recycle codes'". Your hauler's list decides what's recyclable where you live.

The code isn't a recycling promise either. The standard says the codes "are not 'recycle codes'" and that the word "recyclable" shall not be placed next to one.

The EPA says the same from the household end: a resin code on a product "does not guarantee that the product is recyclable in your area." Your hauler's list decides that.

Does the code cover the seal?

In short. No. The code on the lid describes the lid, and the seal is a separate part that usually carries no mark.

Lift the edge of the ring inside a bottle lid, or run a fingernail around the gasket in a lunch box lid. It's a separate piece, pressed into a groove, and the code on the lid describes the lid. The standard assigns a code to each manufactured item, so the ring would need its own mark, and most are too small and too soft to carry one.

Seals on kitchen gear are often silicone. Silicone isn't one of the six named families, so even a coded silicone part would only show a 7, and in practice you'll usually find nothing on it at all.

The same goes for a bottle's spout, a straw, the valve in a sippy lid, and the gasket under a blender blade. Each one is its own part and can be its own material.

Where else can you find out what a part is made of?

In short. The maker's product page, the manual's parts list, the packaging, then an email to the maker, in that order.

When a part is unmarked, go in this order.

1. The maker's product page. Look for a specs, materials or construction section. Some makers list the lid and seal as separate lines. Many list only the body.
2. The manual's parts list. An exploded diagram or a replacement-parts page names each piece, and a spare gasket listing often says what it's made of because that's what you're buying.
3. The packaging. The box or hang tag sometimes carries the resin code or the material in small print, especially on storage containers.
4. An email to the maker. Write down who answered and when.

Each one is good for something and leaves gaps.

Our free kitchen checklist covers twelve everyday things in the same order. The water bottle lid and lunch box seal rows are the two this guide expands on.

What should you ask the maker?

In short. Which plastic the lid is, what the seal is made of, and which parts touch the drink or the food.

Say what you're holding and what you see, then ask three things.

• Which plastic is the lid molded from? If the lid shows a 7, ask which resin a 7 means on that model.
• What is the seal or gasket made of, and can I buy a spare?
• Which parts touch the drink or the food? A straw, a spout, a steel insert inside a plastic cap. Ask for each by name.

If the answer is "we don't disclose that," write it down. Our checklist has a column for it, and "not stated" is an answer too.

Do our products carry a resin code?

In short. No. No part Cristel names on the six pieces we sell is plastic.

Nothing in our store carries a resin code, because no part Cristel names on the six pieces we sell is plastic. The six Cristel pans and pots are 18/10 stainless steel where food sits, with an aluminum core sealed inside the base or the walls, and solid stainless handles on stainless rivets. The lids are borosilicate glass with a stainless steel rim; Cristel does not state the material of the 1826 lid knob, so we do not claim it.

That's the whole parts list, and each product page in Cristel stainless cookware spells it out part by part. This guide is for the bottle, the container and the lunch box already in your cupboard.

Sources

1. ASTM International, D7611/D7611M-26, Standard Practice for Coding Plastic Manufactured Articles for Resin Identification, store listing with the Scope and the Significance and Use sections. store.astm.org.
2. ASTM International, Resin Identification, news item dated 2016-07-26. astm.org.
3. Plastics Industry Association, State Resin Identification Regulation Survey, May 2022, PDF hosted by the Oregon Department of Environmental Quality. oregon.gov.
4. Kentucky Revised Statutes 224.50-585, Plastic resin code labeling. apps.legislature.ky.gov.
5. Riverside County Department of Waste Resources, Plastics. rcwaste.rivco.gov.
6. US Environmental Protection Agency, Frequent Questions on Recycling. epa.gov.
7. Federal Trade Commission, Guides for the Use of Environmental Marketing Claims, 16 CFR 260.12, Example 2. ecfr.gov.
8. Clearly Made, Cristel stainless cookware collection. clearlymadegoods.com (maker statement).
9. Clearly Made, Cristel 1826 Glass Lid. clearlymadegoods.com (maker statement).

Last reviewed October 24, 2026. Next review by October 24, 2027. Spot an error? Tell us and we'll fix it here.