If merino wool is not your game and you’d rather wear a synthetic base layer, check out the budget-friendly REI Base Layer Long Sleeve (L/S) Crew. It’s not the lightest synthetic base layer available, but the price is good, it’s odor-resistant, durable, and comfortable across a much wider range of temperatures than so-called “silk” weight synthetic base layers (which we don’t recommend for most hikers due to their poor durability).