By the button strap do you mean the part that goes over your shoulder? The strap wraps around the shoulder straps so it keep the shoulder straps from falling down?
Sorry for the late reply but yeah that's the one.
Do note that JRZ is old fashion and doesn't use paypal for payments unless they changed things. A payment form is emailed to you that you fill out and send back. I sent a partially filled payment form then called in to have him fill out the credit card info for security purposes.