Epic Supply's clothes are double-layer muslin cotton, pre-washed before they ship, so a newborn wears something soft from day one rather than a stiff new garment that takes a while to soften up. The seams are sewn flat, so there's no ridge of stitching catching on a newborn's neck or wrists. Dyes are chosen with that same care, and muslin's open weave lets air move through more freely than a thicker knit does. For the longer version of why Epic Supply builds around this one fabric, see why muslin is the only fabric Epic Supply uses.
Sizing runs from newborn up to around 4 years, so the same piece can fit a sibling years later. Newborns live almost entirely in onesies, since they're easiest for frequent changes; most parents don't move into two-piece outfits until the baby is sitting up or crawling. Muslin creases straight out of the wash. That's normal, not a flaw, and it relaxes once it's on.
Care stays simple: wash cold on a gentle cycle, then tumble dry low or hang it up. Skip the fabric softener, since it coats the fibers and cuts into the breathability that's the whole point of choosing muslin, and keep the dryer heat low for the same reason. Epic Supply is a small family business, Vanessa and Bob, who design the collection in Bali. They ship worldwide with tracked delivery and take returns within 30 days on anything unworn. If a newborn runs warm, muslin also works well in air-conditioned rooms.