Verdict from 7 user reviews

6 reasons to buy

  • The Grepon 4S GTX’s lightness was appreciated by a wearer.
  • It was a comfortable mountaineering boot, according to an online buyer.
  • A couple of owners noted that it runs true to size.
  • Its resistance to cold was lauded by an alpinist. He added that it remained warm in 20-degrees below zero temperature.
  • An experienced adventurer liked how it was cushioned in the right areas.
  • Several verified purchasers commented that it was an excellent boot for classic mountaineering.

1 reasons not to buy

  • The Millet Grepon 4S GTX has a narrow fit, based on a consumer review.

Bottom line

The Grepon 4S GTX can be considered one of Millet’s successful mountaineering boot. Its performance on alpine conditions was rated highly thanks to its comfortable build, warmth and true-to-size fit. It did not please everyone though. All in all, it seems the Millet Grepon 4S GTX may benefit narrow-footed mountaineers more. Those who have a wide foot might want to consider other options though.

Good to know

  • The brand’s engineers equipped the Grepon 4S GTX with features needed to deliver precision and protection during high-alpine pursuits. The boot’s Gore-Tex-lined 3D mesh polyester upper wards off trail debris and wet elements.
  • Underfoot, it employs an EVA midsole and a Vibram outsole. The former dissipates shock from ground impacts, while the latter renders grip on various terrain types.

This men’s-only mountaineering boot from Millet is manufactured in standard (D) width. It is offered in whole and half sizes. Generally, it runs true to size. The brand also noted that it has a slim toe box. Its lacing system has an automatic lock near the ankle area which enables users to customize tension at the instep and the boot’s shaft.

Millet designers equipped the Grepon 4S GTX with a Vibram Mulaz EVO outsole. Its sturdy profile yields surefootedness on various types of terrain. The clover-like boots at the center provide multidirectional traction. The aggressive lugs at the perimeter create a stable ride while the heel brake enhances the stopping power of the sole.

The Grepon 4S GTX is equipped with an ethylene-vinyl acetate (EVA) midsole for cushioning. It also helps maintain the user’s connection to the ground for a more dynamic response. A crampon-compatible EVA insert is placed at the rearfoot to maximize shock absorption upon heel strike.

The trademarked AFC structure keeps a secure hold of the heel. It prevents heel slippage without limiting the natural movement of the foot.

This high-cut mountaineering boot features a 3D mesh polyester (100% PES) in its upper. This durable material is paired with a Gore-Tex lining inside for water protection and ventilation. Duratherm insulation is incorporated into the laminate to retain heat even in very low temperatures.

Additionally, the PU overlays help maintain the boot’s structure. An abrasion-resistant rubber rand partially wraps the lower part of the boot for added durability.

In the ankle area is a Lycra fabric which allows the foot to flex comfortably. Combination eyelets with a synthetic lace allow for fit management while the pull strap at the heel assists in donning and doffing.

  • This Millet footgear is compatible with hybrid crampons.

How Grepon 4S GTX compares

This shoe: 76
All shoes average: 83
55 97
This shoe: £300
All shoes average: £440
£170 £1180
This shoe: 750g
All shoes average: 868g
530g 1531g
Paul Ronto
Paul Ronto

Paul loves adventure. Over the past 20 years, he has climbed, hiked, and ran all over the world. He’s summited peaks throughout the Americas, trekked through Africa, and tested his endurance in 24-hour trail races. He has worked in the outdoor industry as a whitewater and hunting guide, gear tester, copywriter, and outfitting specialist at places like The National Outdoor Leadership School, No Barriers USA, and Sierra Trading Post. He has been quoted in NYMag, NBCNews, and Business Insider to name a few.