just under 5'10 and around 180 (I know, hit the treadmill fatty) and am wondering what size to get. Have the Mentor in M which is a nice techincal fit and doubt that this would ever fit underneath, well maybe but it would loose a lot of loft. Should i get a M or L to fit over everything for those times when I am standing around freezing?

Tech Specs:

Material:

[body] 20D recycled ripstop polyester; [hood] 20D recycled ripstop polyester; [shoulder] 30D Pertex Endurance (nylon); [arms] 30D Pertex Endurance (nylon); [lining] 25D polyester 

Insulation:

650-Fill down 

Fabric Waterproof Rating:

water-resistant 

Fit:

regular 

Venting:

no 

Pockets:

2 front, 1 chest, 1 internal 

Hood:

yes, full-time 

Weight:

L 1 lb 5.9 oz 

Recommended Use:

mountaineering, climbing, winter camping, multi-day touring 

Manufacturer Warranty:

lifetime