No matter the leather, a B25 is small enough that it may keep its form for an extended length of time than a B30 The pontets, or metal rings, on the initial Birkin are closed (just like the pontets within the Haut A Courroies product). The pontets on subsequent Birkins https://jaspergmsyd.blogminds.com/the-ultimate-guide-to-birkin-epsom-leather-32238413