Rab Alpine Bivi vs Tennier Military Modular Sleep System

The Rab Alpine Bivi is a great Bivy Sack for its $250 asking price.

The Tennier Military Modular Sleep System, however, while a reasonable product for $449, doesn't stack up against its competitors quite as well. If you're considering Bivy Sacks in the $450 range, you might want to check out some better options.

Popular Mechanics, a review site with a history of doing objective hands-on testing, has great things to say about the Rab Alpine Bivi. In fact, it's "Ranked 1 out of 8" in its "The Best Bivy Sacks for Any Outdoor Adventure" roundup, which points toward it being a good Bivy Sack.

Moving on to the Tennier Military Modular Sleep System: no sources that perform reliable and objective hands-on testing have included it in their Bivy Sack roundups, which usually means that a product doesn't make for a good purchase.