The ring is 6mm wide (about 1/4"). It is made of aluminum and it's adjustable in size. I have them in two sizes, the S-M will fit sizes 6-9, the L-XL 9-13.
Please write in the "Special instructions to seller" box at checkout what you want stamped on the ring.
The letters are hand stamped one at a time so they might not be perfectly straight or centered which lends itself to the unique handmade look of each ring.