The Secret History of the Tri-Glide Slide

Close up of a tri glide slide
Image credit: Rodger Evans / CC BY-ND 2.0

In writing this week about the baseball cap, I got stuck on a detail that didn’t make the final edit of that piece but did send me down an online rabbit hole featuring several dubious message boards, patents spanning several decades, and, briefly, a three-wheeled motorcycle*. All in search of the story of elusive — and delightfully named — tri-glide slide. 

If you haven’t encountered this tuneful triplet of syllables before, the tri-glide slide is a flat, square, adjustable loop that regularly features on harnesses, diving masks, bra straps, and — the item that sparked my own interest — baseball caps. It also goes by webbing slide, tri-glide buckle, or plastic slide.

  • Man hiking in a white shirt and baseball cap
  • Tri-glide slides on the back of several yankee caps
  • Man wearing a backward baseball cap and tracksuit top
Image credits: Chase McBride on Unsplash; image of stacked baseball caps is my own / All rights reserved; Ralph Rabago on Pexels

What is the origin of this unremarked but essential bit of gear? This type of cinching tech can arguably be traced at least as far back as the development of the stock (read: cowboy) saddle, which opted for variable adjustment around a horse’s barrel (read: stomach) rather than girths (read: belts) used on English saddles. But perhaps the most direct source of the webbing slide in clothing appears in Britain in the early 1900s. 

  • Arthur P. Reynolds saddle cinch illustration 1940
  • Edith Towner horse hair saddle cinch illustration 1937
  • Harry Mann Waddell horse hair saddle cinch illustration 1936
Cinches used with Western-style stock saddles
Image credit: National Gallery of Art / CC0 1.0

Between the Boer War and the start of the Great War, there was a significant change in military gear. Traditional leather belts and harnesses slowly began to give way to a more functional material in the form of cotton webbing, an innovative bit of kit first developed for the British army by the recently founded Mills Equipment Company. 

But with new material came new requirements. Unlike leather bands, which came fitted with buckles and punch holes, webbing allowed for variable and minute adjustments but required a mechanism that enabled smooth and secure fastening. As a simple but inspired solution, enter the grandparent of today’s tri-glide, which can be seen below.

Mills Equipment tri-glide slide on webbing military equipment
A Mills Equipment Company webbing slide
Image credit: Auckland Museum / CC BY 4.0

In the decades since Mills Equipment’s innovation, webbing (albeit no longer necessarily in cotton) has become standard military issue across the globe and the lowly webbing slide — whether in metal or plastic, on a military belt or civilian cap — continues its ubiquitous and unsung service.

*If you’re wondering, the motorbike detour was courtesy of a model of Harley-Davidson called the Tri Glide Ultra, in case you happen to be in the market for a three-wheeled hog.