Sleeveless Base Layers

Which material is best?

• Wool: highly moisture-wicking and odor-resistant
• Synthetic: durable and less expensive
• Silk: soft and lightweight for casual activities

Match the temp to the trek

• Lightweight layers: best for moderate to cool temperatures
• Midweight layers: best for cold temperatures
• Heavyweight layers: best for below-freezing temperatures

Find your fit

• Must be close to skin to efficiently wick sweat; should fit comfortably snug
• Base layer is for moisture control; your mid layer is for warmth

Key features to look for in hike clothing

• Moisture wicking: moves sweat to the outer surface while also drying quickly; that lets you break a sweat without feeling clammy or chilled
• Sun-protective fabric: Choose clothing with a UPF rating to protect yourself from harmful UV exposure; a higher rating means better sun protection
• Quick drying: materials that dry quickly keep you cool, comfortable and dry
• Insect repellent: treated with active ingredients to help keep ticks, mosquitoes and other bugs at bay

Hike clothing fabrics

• Merino wool: has fine fibers that make it soft, breathable, moisture-wicking, reasonably quick to dry and not prone to retaining odors.
• Polyester/nylon: Generally less expensive than merino wool, these synthetics excel at wicking sweat and drying fast; many incorporate recycled materials 

Dress in layers 

• Start with a base layer that wicks sweat off your skin; this includes underwear, a bra, hiking shirt and hiking pants
• Add a middle layer to retain body heat in colder conditions; this could be a fleece jacket, an insulated vest or puffy jacket
• An outer layer, like a rain jacket, shields you from wind and rain

Fabrics

• Synthetic: moisture-wicking, quick drying, durable, but can hold on to odor
• Wool: moisture-wicking, odor-resistant, cooling in warm weather, can be less durable

Styles

• Bikini: less rear coverage, thinner waistband, higher-cut leg
• Briefs (women's): full-cut briefs offer more coverage in front and back; hipsters offer medium front coverage and back with higher rise

• Briefs (men's): close fit and good support, but less thigh coverage

• Boxer brief or boy shorts: snug fit, good coverage, longer cut extends down to the upper thigh
• Boxers: looser fit, added coverage can prevent chafing but prone to bunching
• Thongs: lightweight and quick-drying but provide the least coverage
• Sports bras: compression and support during high-output activities like hiking and running