It’s a common misconception that the plastic cartridges used to power pens and pencils are made from recycled materials.

But that’s not the case, according to the Food and Drug Administration.

Instead, these recycled materials are often made from the materials that were used in the production of the products themselves, said David Sperling, the FDA’s deputy commissioner for enforcement.

“A plastic cartridge can be made from polyester or polyurethane, both of which are used in plastic manufacturing,” he said.

The FDA also says it’s important to note that some of the recycled materials used in a plastic cartridge battery are not actually made from these recycled polyester and polyuretha, but rather from polyurethan, polyester resin, polyethylene, and polyethylen vinyl acetate, which is commonly found in many consumer products.

But the recycled polyureas aren’t all that common, so when it comes to recycling plastic cartridges, it’s best to use recycled materials that have a lower recycling rate than what’s used in these products.