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the OMM Mountain Core Jacket
the OMM Mountain Core Jacket
See our entire range from the OMM here!
The OMM Mountain Core Jacket is a high-performance insulated jacket designed for variable intensity activities in mountain and trail environments . By combining PrimaLoft® Active insulation with OMM's own lightweight, stretchy and windproof Flexile shell , the Mountain Core creates a garment that provides reliable warmth without compromising breathability .
PrimaLoft® Active is a synthetic “down-like” fiber woven through an open knit mesh , creating a high-loft structure with effective insulation. The result is fleece-like warmth at less than half the weight , while allowing excess heat and moisture to escape at higher intensities. This makes Mountain Core ideal for fast climbs, mixed tempo sections and chilly descents.
Like OMM’s other Core products, the Mountain Core is designed to perform both wet and dry . Synthetic insulation combined with excellent moisture transport means the jacket continues to warm even in damp weather. With 125 g/m² PrimaLoft® Active , with approximately 64-65% of the insulation coming from recycled materials , performance is combined with a more sustainable material choice. The insulation is also bluesign® and OEKO-TEX® approved .
The stretchy Flexile nylon/spandex shell provides high wind resistance and some water repellency , while maintaining good ventilation – perfect for changing conditions. The Mountain Core is designed to work alone in dry, cold weather , or under a shell in rain and strong winds for added protection and insulation.
A softly lined hood with a discreet visor provides extra comfort and protection against cold winds, and the jacket's functional details make it an obvious choice for mountain running, trail running and long days in chilly environments.
PrimaLoft® Active 125 g/m² – warm, lightweight and extremely breathable insulation
Warm even when wet – synthetic insulation for demanding environments
Flexile shell (nylon/spandex) – wind resistant, stretchy and flexible
High breathability – for activities of varying intensity
Lined hood with soft peak – protection against cold winds
Can be combined with a shell jacket – maximum flexibility in bad weather
Stretch panels
Wind-resistant construction
Warm even in humid conditions
Large fleece-lined hand pockets
Hidden zippered chest/inner compartment with key clip
Full-length YKK® zipper
Fleece-lined hood with soft peak
Insulation : PrimaLoft® Active 125 g/m²
Recycled content : approx. 64–65%
Material (outer fabric) : Flexile (nylon/spandex blend)
Surface treatment : DWR (Durable Water Repellent)
Weight : approx. 400 g (size M)
Trail running, mountain running, hiking, mountain tours and active days in cold, windy and changeable weather , where you need insulating warmth that breathes while moving .
Wash according to manufacturer's instructions. Avoid fabric softener to preserve the function of the insulation and DWR treatment.
The OMM Mountain Core Jacket is an insulated jacket with PrimaLoft Active and a stretchy, wind-resistant outer fabric. This is the men's model, which has a relatively roomy Regular Fit to be worn over a base layer and a thin midlayer.
Start primarily from your chest measurement. Also check your body length and waist measurement and consider whether the jacket will be used primarily as an outer garment or under a shell jacket.
| Size | Breast | Body length | Waist |
|---|---|---|---|
| XS | 80–86 cm | 155–162 cm | 70–76 cm |
| S | 86–92 cm | 162–173 cm | 76–81 cm |
| M | 92–102 cm | 173–183 cm | 81–86cm |
| L | 102–110 cm | 178–188 cm | 86–92 cm |
| XL | 110–117cm | 185–193 cm | 92–97cm |
The measurements in the table are body measurements, not the jacket measurements.
OMM insulation garments typically use a Regular Fit, with more room and a straighter cut than the brand's body-hugging running garments. The Mountain Core Jacket is designed to be worn comfortably over a first and second layer, while also functioning under an outer layer when the weather calls for extra protection.
The jacket should follow the body without being tight. PrimaLoft Active insulates by creating air pockets in the material, and a garment that is too tight can compress the insulation and reduce the space for warming air.
Normally choose the size that corresponds to your chest measurement.
As an active outer layer: Normally choose your usual OMM size. The jacket should allow space for a base layer or a thin functional shirt.
Over base layers and thin mid layers: Regular Fit should usually provide enough room in your normal size.
As a warming reinforcement garment: Consider a size larger if the jacket will regularly be worn over multiple layers during breaks or after completing an activity.
Under a shell jacket: Don't choose a size larger than necessary. Make sure that both the Mountain Core Jacket and the shell jacket can be closed without compressing the insulation.
Chest: Measure horizontally around the widest part of the chest. Let your arms hang relaxed.
Waist: Measure around the natural waist without tightening the tape measure.
Body length: Measure barefoot from the floor to the highest point of the head.
Please measure and try on the same layer that you plan to wear under the jacket.
Close the jacket over your planned layers and check that:
The right size should allow room for functional layers and preserve the volume of the insulation, while still allowing the jacket to feel flexible during movement.
