The tables below highlight the differences between the M1200 (regular fit) and M3600 (slim fit) shirts. As a general rule, our slim fit Fred Perry Shirts will be narrower in the body by approximately 3cm each side to create a slimmer fit. Our slim fit styles will also have a slightly smaller collar and shorter overall length, to keep everything in proportion and to maintain a tailored, slim-cut style. Fred Perry create many variations of the classic twin-tipped shirt each season. If you are unsure of the sizing of a particular style, please contact Customer Services, quoting the style number (e.g. M1234) of the item you are interested in. M1200 (regular fit) XS S M L XL XXL Half Chest (cm) 45 49 53 57 61 65 Length (cm) 68 70 72 74 76 78 M3600 (slim fit) XS S M L XL XXL Half Chest (cm) 41.5 45.5 49.5 53.5 57.5 61.5 Length (cm) 66 68 70 72 74 76 NB: ‘Half Chest’ relates to the measurement of the garment when laid flat, measuring across the chest from 2cm below each underarm. Double this