Three-button jacket, made in London, with a tropical worsted — "summer wool" — woven with the wool of sheep from Yorkshire in Yorkshire, and horn buttons from the Midlands. The SB3 is a fairly casual and unstructured jacket, but it does have some shape to it — especially in the body. Thus, if between sizes — if only slightly between sizes — then it is recommended to go up a size. Dry-cleaning really is the only thing for this jacket. But, since the cloth is, down to its fibres, so naturally resistant to grease and grime, and is anyway anti-microbial and odour, then dry-cleaning need not be undertaken very often.