Men's Base Layers

Stay warm and dry in the harshest conditions with 509’s Active Layering System featuring Cold Armor technology. Pairing 509’s base and mid layers w...

KLIM SIZING CHART We built the Inferno to be one of our most versatile and comfortable pieces that excels at mid-layer performance as well as bein...

The 509 FZN Base LVL 2 Pant offers mid layer insulation - the secret weapon for warmth and comfort. A comfortable mid layer is built from a polyest...

Stay warm and dry in the harshest conditions with 509’s Active Layering System featuring Cold Armor technology. Pairing 509’s base and mid layers w...

It’s always about to pop off when you’re wearing the 509 FZN Merino Party Suit. This one-piece base layer is made with warm, breathable, temperatur...

With the 509 FZN LVL1 Party Suit, there’ll never be a question of who’s ready for a good time. This one-piece base layer is made with a warm, hard-...

Add the ultimate base layer to your day with the 509 FZN Merino Crew Shirt. Made with a Merino/spandex blend for stretch and all-day comfort, this ...

Every successful day on the sled starts with a good base layer, and the 509 FZN Merino Quarter-Zip Shirt knows this better than most. Made with a M...

Slide on a new level of luxury, because the 509 FZN Merino 180 Boxer Shorts have been made with a stretchy Merino/spandex blend for all-day comfort...

KLIM SIZING CHART KLIM Aggressor Cool -1.0 Sleeveless Shirt KLIM's Aggressor Cool -1.0 Base Layers provide a level of cooling and comfort never bef...