Belts are becoming so 20th century.

The trendlet

That's because as made-to-measure (read: perfectly tailored) suits continue their stylish rise in popularity, men are letting go of the loops and opting for sleek trouser adjusters. Quietly situated on the waistbands of well-made pants, the adjusters — also known as side tabs — can feature buttons or metal sliders.

Where do they come from?

In the late 1800s, when tailors on London's Savile Row were refining the tailored suit, trouser adjusters were the standard mechanisms used to let waistlines in and out (particularly useful now when one may have had one too many tacos).

In 1922, Levi Strauss & Co. added belt loops to its classic jean, as workingmen needed a way to hold up their dungarees. Later in that decade, tailors of men's dress pants began adding similar loops. The style of the day called for pants to fall below the natural waistline, making belts functional.

From then on, belt loops have been standard on men's pants, although tuxedos often feature only side tabs.

Tailored suits have been a part of millennial haberdashery for the better part of five years now. But in the last two years, a throwback to all things classic has men asking their suit guys for side tabs. This spring, look for the adjusters on not just flat-front pants but on better-fitting pleated ones as well.

Who is wearing them?

Tung To, owner of the Center City men's shoe store ToBox. Robert Bennett, a Philadelphia financier. And guys who prefer a modern look.

Would Elizabeth’s guy wear them?

She would hope so.

Should you wear them?

Sure. It's a great way of subtly showing you care about the details.

These pleated and flat-front trousers, $250, are available at Robbini Bespoke at $250., 609-685-3484. Model, Robert Fung.