Mountain Core 125 Synthetic Sleeping Bag

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The Mountain Core is a synthetic sleeping bag lined with Primaloft’s ACTIVE insulation. This ultralight bag is ideal for mountain racing where weight and pack size are critical. 

OMM says

An ultralight sleep system with great next to skin comfort and breathability. Primaloft® ACTIVE is used as the liner fabric to give an open fleece feel but with the added benefit of an unrivalled warmth to weight ratio for any fabric. It’s not quite the all out stats winner of Mountain Raid sleeping bag but if you are heading to warmer climates it solves any clamminess issues. Externally, sonic fabric gives great windproofness and the total package retains the packability you’d expect from OMM.

Our Verdict

OMM’s Mountain Core 125 Synthetic Sleeping Bag uses a unique combination of Primaloft Active insulation and PointZero outer fabric. With this combination you are getting insulation with an excellent warmth to weight ratio and a highly wind resistant outer fabric. This sleeping bag is ideally suited to mountain marathons where weight, pack size and efficiency are key. In reality it is a summer bag but you can always extend its use by wearing more clothes during colder conditions. 

Primaloft is the leading synthetic insulation in the outdoor world and its use guarantees you are getting the maximum insulation value for the minimum synthetic weight. The Pimaloft Active used in this bag is used across OMM’s Core range, usually for active insulation where breathability and moisture management are key. This bag certainly isn’t aimed at being the warmest but the users it is aimed at are probably not too concerned by that. Down bags are of course warmer for a given weight but some people prefer the synthetic bags because of their durability and wet weather performance, particularly if you use a bivy or sleep under a tarp regularly.

– Reviewed by Ultralight Outdoor Gear

Features

• Soft textured Primaloft® Active insulation 
• Continues to insulate even if wet 
• Half YKK® zip 
• Stitched through inner with loose laid outer 
• Fast drying easy care 
• Hood drawcord 
• Hang loops at base

Specifications

• Weight: 388g (excludes storage bag)
• Pack size: 21 x 13cm
• Length: 195cm long mummy shape
• Shoulder Width: 65cm 

Material

• PointZero® – 100% 22gsm nylon ripstop fabric, downproof, highly wind resistant with DWR 
• Primaloft® Active: 125g 
• 1.4 tog when dry
• 1.0 tog when wet

Help and advice:

• The Ultimate Guide to Lightweight Sleeping Bags
• Time-Saver Guide to Choosing a Sleeping Bag
• The EN13537 Standard
• OMM Core Technology Explained