Why We Chose The OMM Mountain Core 125: Cosy interior, ultra-light design, super-compact, Primaloft Active
OMM (Original Mountain Marathon) are specialists in featherlight, minimalist gear designed for ultra marathons, hardcore trail running expeditions and ultra-light backpacking adventures. The OMM Mountain Core 125 sleeping bag is no exception. At 380g, it’s insanely light and packs down incredibly compactly (to a size slightly wider and taller than a 1L Jetboil pot). It’s far from the warmest sleeping bag on the market, and we certainly wouldn’t reach for it on anything other than the warmest of nights, but for balmy summer adventures where every gram counts this is a weight-saving dream.
Who Is The OMM Mountain Core 125 For?
This sleeping bag is perhaps best-suited to ultra-runners participating in long-distance, self-sufficient events involving overnight stops, where the lightest possible gear is required. It’ll also appeal to ultralight backpackers who are obsessed with getting their backpack weight as low as possible.
At 380g and sized 21x13cm when packed away, the minimalist approach is undoubtedly impressive – but this comes with a big compromise. The warmth provided from this sleeping is, unsurprisingly, minimal, so it’s only really suitable for warmer summer nights (or campers who don’t feel the cold too badly and are happy to prioritise weight over comfort). We imagine it’ll be used more abroad than in the UK, considering our relatively cold climate.
Warmth & Insulation
The insulation in this sleeping bag is Primaloft Active, which is used as the liner fabric to give an open, high-loft fleece feel. This delivers a good warmth-to-weight ratio. OMM state the Mountain Core 125 provides a 1.4 tog rating when dry, but no EN/ISO ratings (the usual comfort and comfort limit grades for sleeping bags) are published. One particular benefit of Primaloft Active is that it continues to insulate in wet conditions, and OMM claim a 1.0 tog rating if the sleeping bags gets wet from rain or condensation. There’s a 125g fill weight of Primaloft Active in this sleeping bag.