This is a limited edition item of 300 pieces, available when the book was pre-ordered. I have worn it a few times. There is some aging. The following is a quote: The cross-section is rounded to fit the hand. The back is stamped with "MB". You can enjoy the aging process as you use it. Also, the black color has a unique luster due to the black coating on the brass, giving it a luxurious finish. - Size: Free - Width: 4.5mm - Thickness: 1.5mm - Wrist circumference: Approximately 157mm Thank you for viewing.