acoustic strap secure for metric threaded endpin jacks, made in USA, brass For endpin jacks! Peace of mind for non-slip strap attachment to an acoustic guitar endpin jack. Acoustic Strap Secure installs on your strap and threads onto the jack to replace the stock button. You can play plugged in or unplugged, knowing your strap can't slip off. Works for both straight and right-angle cables. Easy-grip knurled edges. Crafted from solid brass or stainless steel to last a lifetime. For standard jacks: A perfect fit for Switchcraft, Fishman output jacks and more. Standard thread: 3/8&;quot; x 32 Outer diameter: 3/4&;quot; (19.05mm) For metric jacks: Fits L. R. Baggs and the jacks found on many imported acoustic guitars. Metric thread: M9 x . 75 metric Outer diameter: 3/4&;quot; (19.05mm) Might require you enlarge the hole in your guitar strap.