This lovely Stainless Steel essential oil car diffuser is made made of  316L stainless steel which makes it resistant to corrosion and rust. These lockets are 38mm 
Six colored diffuser pads are provided free with them. You may choose one of these 10ml essential oil blend:
Mandarin
Tranquility
The Alchemy
Just open the locket, insert a felt disc and add one or two drops of essential oils. Diffuse your favorite scent for up to a week before it will need to be refreshed.