This just in from Albert Thurston. Sounds much the same as the response Bic recieved. I bought the red and the royal blue at the very end of the Box Cloth Braces page on the Thurston site. Forward . . . The 'catgut'(no cats involved) was the part that used to connect the buttonholes at the front, and was originally made for the long line fishing industry - it was superseded by nylon monofilament in the 1970's - and we have been unable to get the relatively small quantities we use for some years. Having said that we have gone back to the way we used to make them - the gut was always covered with white gloving leather prior to the 1960's, and all we have done is substitute the gut inner part with a modern, and better, alternative. The button holes are still hand stitched. These are the ones you purchased, and in our view they are better than the 'catgut' ones as we have had no returns due to breakage ( which was a constant problem with the catgut ). The braces you have received are visually identical to ones in our 1870 catalogue, and have been worn by the great and the good ever since. Thanks for your order - enjoy them.