What is the difference when the slacks fastening is a side invisible zipper instead of being at the front?

Usually, slacks have a zipper and button in the center of the front fly, causing multiple layers of fabric to overlap. RE RHEE's straight wide-leg trousers leave this front closure empty and place an invisible zipper on the side seam^[2]. Because the zipper teeth are not exposed on the outside and interlock like a seam line, the silhouette of the side seam also connects smoothly.

This structure makes a clear difference when tucking a top into the pants. Without a zipper fly or button bulk at the front, the abdominal area stays flat rather than bulging outward. As a wide straight fit that extends straight down below the waistline, the clean texture of the front naturally reaches all the way to the hem^[3].

The waistline is also much more comfortable when wearing the belt included as a standard component^[4]. The zipper pull or button flap does not clash with the belt buckle to lift under outer garments.

hmmm, simply quietly shifting the familiar front button to the side seam clears the center line of the pants, revealing a smooth, flat surface.