So someone wants to hide something in a couch and installs a ZIPPER instead of sewing it closed again??
Sofa cushions have zippers on them, so you can take the covers off to clean them, or replace the foam insert if it’s too lumpy or the cat peed on it.
Most all sofa cushions that are removable have zippers. It's easier, cheaper, and faster than tying to sew them shut after they've been stuffed. Worked in the furniture-making biz for a few years. Stuffing cushions sucked. It was made easier with a vacuum and some silicone spray (wrap the foam in light plastic, vacuum shrink it, put the cover on, release the vacuum, then work the foam into the corners and zip 'em up.