Kitchen Sliding Window Rollers

The rollers themselves are about half inch in diameter on the outside and 3/16 wide, and have a metal outer ring and a brass inner axel. The rollers rests in a u-shaped metal saddle which rests inside the plastic casing. Looking at it from the bottom, the plastic holder is about 9/16 long and about 7/16 wide.

I believe I found it by scrolling through your site. I've ordered 2x Part 87-186. I hope that's the one.