I think base layers are great. They wick moisture off your skin and add an extra layer of comfort between you and the outside world. You can wear them under an insulation layer or shell, or if it is warm enough, by themselves. And at night, they make great night clothing, whether you are snuggled up in a down sleeping bag, or are sleeping between satin sheets.

One of my favorite base layers are the Extend base layers from Mountain Hardwear. I use their Extend Zip-T (top) and Extend Tights (bottoms) on most of my adventures. The only exception is when it is sweltering hot, and then, not much other than an air conditioner can really keep you comfortable.

Here's what I like about the Extend Zip-T and Tights:

• While Mountain Hardwear does not assign a "weight" to this base layer, such as silkweight, lightweight, midweight, and so on, I would personally put them in the lightweight category, although some people might argue that they are closer to a midweight. I generally prefer lighter weight base layers as they are more versatile than heavier weight base layers. For example, for bitterly cold temperatures, you can wear two pair of lightweight base layers.
  
   
• The fabric is made of Polartec Power Dry. This is a 100% polyester fabric that has a bi-component knit construction. This means that the fabric is different in the inside (against you skin) than it is on the outside. The inside layer is designed to wick away moisture, and the outside layer is designed to move the moisture to the surface where it can better evaporate. The fabric is very soft to the touch and very comfortable.
  
   
• The fabric has been treated with a permanent anti-microbial finish which does a relatively good job of keeping the odor down over extended periods of wear without washing.
  
   
• Unlike most base layers, the seams are not in the places you normally see. They have been moved so that they won't accidentally abrade your skin. This gives the garments a kind of "futuristic" look.
  
   
• Lycra has also been used on some parts of the these two base layers to provide added stretch in those areas where it comes in handy, such as the cuffs, neck, side panels, and at the ankles.
  
   
• The zipper on the Zip-T is deep, about 8 inches, and is useful to help regulate moisture and temperature.
  
   
• The fabric dries very fast, so if you want to rinse them out, they will dry very fast, especially in the sun.
  
   
• The Zip-T weights about 8 ounces and the Tights weight about 7 ounces.

While you can purchase the Zip-T and Tights separately, I would recommend getting them as a team. I hope Mountain Hardwear intends to keep these products in their line with few or no changes, as they are virtually perfect just the way they are now.

Using the Extend Base Layers in the Real World

In warmer weather, I use the Zip-T by itself. It doesn't really look like your conventional base layer, so nobody will be able to tell that it is "long underwear". The Zip-T breathes very well and is very comfortable up to 80+ degrees.

When it gets a little cooler and windy, I'll cover the Zip-T with either a wind shirt or a soft shell for protection. Or if it is pouring rain, I'll slip a waterproof Gore-Tex shell over the Zip-T. This is a good combination for cool to warm temperatures as the Zip-T does a good job of absorbing any excess moisture that the jacket can't get rid of.

In cold weather, using the Zip-T along with a fleece or down insulation works well, adding an extra protection of warmth and flexibility as the weather changes or your physical activity level changes.

I generally don't wear the Extend Tights until the weather gets cold, as my legs aren't all that sensitive to cool weather. I generally wear the tights along with hiking pants or soft shell pants. In temperatures down to about 15-20 degrees, this is all I need to stay warm when active.

When traveling, I often bring along two pairs of the Extend base layers. One pair to use during the day, and the other pair at night to sleep in. This allows my daytime pair to air out over night, extending how long I can wear them without washing them. And if it gets really cold, I can wear both pairs at the same time.

I also might mention that the Zip-T fits snugly over your torso, but not too tight. The tights also fit tightly, perhaps a little more snugly that the Zip-T does.

The Extend base layers are also relatively wrinkle-free. I have worn them many days in row, and unless you spill your dinner on them, it is hard to tell that you have lived in them for days at a time.

Recommendation

If you explore the outdoors, you need a quality base layer, and you can't go wrong with the Mountain Hardwear Extend Zip-T and Tights. I highly recommend them.

Product Notes

Both the Extend Zip-T and Tights are available for both men and women in a wide variety of sizes, and in three colors. Mountain Hardwear also makes a crew version of the Extend Zip-T (no zipper) if you don't care for zippers. The Zip-T retails for $60.00 and the Tights retail for $48.00.