Have you noticed that lots of sleep products have zippers, but they don’t want you opening their covers? It’s probably because of fiberglass.
The zipper on your mattress is only for manufacturing convenience. They need the zipper to make the bed, but they don't want you opening it. Why? Because the inside layer is probably filled with fiberglass. Right under the pretty white soft knit outside, only a quarter inch from your nose, is a layer of fiberglass. They don't want you opening that up and vacuuming it because it would spread fiberglass all over your bedroom, onto your children and pets, and cause absolute chaos. Best leave the fiberglass layer alone.
But that means you can't vacuum out the nasty and make your environment cleaner and lower your exposures to chemicals and allergens. But what do they care, they've already sold you their mattress: now it's your problem.
You can tell if it's fiberglass.
If you look very closely, you can see a kind of hairiness that sticks up, and that's the fiberglass. We don't use fiberglass. We use a proprietary and patented blend of para-aramid fiber (used by firefighters around the world in their apparel and totally chlorine free FR Rayon, a combination that is effective, and as clean and environmentally sensitive as possible). It’s super soft, and there is no fiberglass!
Don't believe your bed is filled with fiberglass? Just ask.
Some of them are quite open about it: it’s right on the mattress tag. Some hide behind other phrases, trying to fool you, but the federal government requires them to be honest about the content. It's illegal to mislead you about these materials: push. Ask questions. If you're in the middle of your 100 night trial and this makes you unhappy, send it back.