The width refers to how wide you would like your band to be, the material is available in the following sizes
D shape 1.5mm 2mm 3mm 4mm 5mm 6mm
Flat Shape 1.5mm 2mm 3mm 4mm 5mm 6mm 8mm
Oval shape 3mm 4mm 5mm in a court /oval shape
The depth is set and is usually around 2mm maximum at the deepest part of the ring, it is not possible to change the depth unless you are making a flat shaped ring in which case you can make it narrower during your workshop.