You’ll often see terms like “Belgian flax” and “European linen” used to describe various linens. Some of these are in the name, some aren’t—Pottery Barn’s sheets are named Belgian flax, while The Citizenry’s sheets mention that they’re French flax but sustainably made in Portugal. So what does it all mean? Which is best?

Europe has a long history of growing flax and making linen. It’s a preferred source, particularly Belgium and France, which is why some sheets will call out those countries specifically. But according to World Linen, there isn’t a huge difference among European countries—it’s mostly a marketing tactic. You’ll likely be just as happy with any European source of linen, and there is a European Linen certification sheets can receive to confirm that’s where they’re sourced from.

Having Europe in the name doesn’t necessarily mean it was made there, though. After the flax is grown, it needs to be processed, spun, and woven into sheets, which may or may not happen in Europe. Some companies use the term “Belgian flax” or “European flax” to signify that the flax is from that area, but it wasn’t processed there. Some companies make sheets in other European countries, like The Citizenry’s Portugal-made sheets, while other makers might do production outside of Europe, like Quince, which processes its sheets in China and India.

Another term you might see when shopping for linen is something like “woven to 160 GSM.” This describes the weight of the fabric. (“GSM” stands for grams per square meter.) It’s similar to silk, which is also described in weight rather than thread count to give you a more accurate idea of how heavy the sheets will be. The rule of thumb with linen is that under 150 GSM is light, between 150 and 300 is medium, and anything over 300 is heavy.

Weight is also something that shouldn’t change about linen: It’ll get softer over time, but it won’t get lighter. If you have a preference for a certain weight of sheets, you can see whether these details are included to find out exactly what you’re buying.