buckles

I'm currently looking to replace the buckle of my pair of engineer boots, and i've been looking online for this type of buckle where it's rectangular, flat, and has a roller. I can't seem to find anything similar online from typical leather hardware stores. Does anyone have any idea where to...

IMG_0365 by Hawkmoth posted Oct 25, 2016 at 10:18 AM I know it's not a Jacket, but I am hoping that some of you vintage appreciating folks may be able to help? I bought a few of these Buckles a year or two back . Told they were New/Old stock from WW2. I can't find any reference to them...