Another fun use for Prayer Box Pendants is to place a Harmony Bell inside that produces a gentle chime. Worn as a low necklace during pregnancy, the pendant creates a soft, soothing chime that babies learn to respond to during the second trimester. Mothers often shorten the chain after the baby is born to safely continue hearing the comforting chime. Our 12mm Harmony Bells will fit inside the following prayer box/oil diffuser styles - #002, #003, #004, #005, #006, #007, #008, #4, #35, #43, #55, #74, #91, #75, #101, #217. Our 16mm Harmony Bells will fit inside the following prayer box/oil diffuser styles - #4, #35, #43, #55, #74, #75, #101, #217.