The D'Addario Deluxe Series. All feature an exclusive tapered contour designed to prevent twisting when used with acoustic guitars. The body of the straps is 4" longer than standard straps, giving you maximum adjustability from 44.5" to 53" long. 
Note Please view photo this is a fine leather strap with a pleated pattern, cannot be engraved.  

D'Addario Cantanella Leather Guitar Strap