IWC Strap Alligator Marron Brown For Pin Buckle XS (IWA54581) This luxurious IWC Marron brown alligator leather strap in size XS is suitable for use with a pin buckle and can be worn on any IWC Portofino Handwound watch under references IW5101/ 5164. If you require any assistance finding the right strap for your IWC watch, you can fill out our strap finder form here. A member of the Jura Watches team will get back to you as soon as possible with some options.