I use these all the time and they are nearly always accepted at the large letter rate, provided that you don't add any additional packaging other than a padded envelope. I have tried adding ribbon, an elastic band or the box's own protective cardboard cover - all of these make the parcel just too thick to pass smoothly through the slot. If you're happy with that it's an excellent product, smart, reasonably priced and versatile. As well as pendants, it is wide enough to take most slim ladies bangles and it has holes for earrings too!