This post may contain affiliate links.

REI Merino Midweight Half-Zip Base Layer Top Review

REI Midweight Merino Half-Zip Base Layer Top Review

REI’s Merino Midweight Half-Zip Base Layer Top is a 200-gram wool base layer available in men’s and women’s sizes.  It falls between Minus 33’s mid-weight Sierra 1/4 Zip (230 gram) and the Minus 33 lightweight (170 gram) 1/4 zip tops, at a comparable price.   However, REI frequently has these on sale, and you won’t ever find Minus 33 on sale.

I’m a rather big fan of merino wool base layers and hiking clothing.  I find Merino wool to be very comfortable and noticeably less stinky than synthetics. This is even true of blended garments. But you need to care for Merino properly to make it last. That can be annoying depending on the garments care instructions.

Washing Merino Wool

One should always check for washing instructions on any Merino products since the instructions vary quite a bit by the manufacturer. Every Icebreaker wool garment I own calls for “line dry only” which requires vigilance in the laundry room to make sure nothing sneaks into the dryer that shouldn’t be there.  This REI shirt is machine washable, gentle cycle, with likable colors, and the instructions recommend drying at a low temperature.  I have a front loading washer, so I just wash it with everything else rather than running a gentle cycle.  After 9 washes and dries, it is still like new and hasn’t shrunk.


The Merino Midweight Half-Zip Top is sewn with flat seams to reduce chafing.  It has underarm gussets to improve range of movement and a drop tail hem for coverage which helps keep it below the hip belt on your pack.  The half zip gives you plenty of ventilation when needed.  The mock neck is snug enough to keep out drafts without choking you, and your neck and chin are well protected from the zipper.  The top is also available in some nice colors, like this blue either.

The Half-length Zipper provides plenty of ventilation.

At 200 grams, REI’s merino fabric is a reasonable weight for a base or second layer in cold weather.  Note that you should choose your merino layers based on the weight (grams) rather than “lightweight” and “mid-weight” nomenclature since one company’s light could be the same as another company’s mid.

Wool fabric is measured by weight in grams per square meter (gsm) of the fabric. The larger the gsm, the heavier and the warmer the garment.

  • Very lightweight: less than 150 gsm
  • Lightweight: 160-190 gsm
  • Midweight: 195 – 250 gsm
  • Heavy: Greater than 250 gsm


Now for the fit.  This shirt follows a current trend toward snugness in women’s long sleeve knit tops designed for an athletic user.  The sleeves are very snug on me, especially in the upper arms.  This is fine on a base layer, but putting it over a short sleeve shirt can result in bunching of the short sleeves. I recommend trying one on before buying if you can.  The sleeves are quite long and do not include thumb holes to help justify the long length.  Granted, I’m kind of short (5’3”), but I got a small and the sleeves are 2” too long.  I’d like to see shorter sleeves in a small.  If I had gotten a medium, there may have been a slight improvement in the tightness, but the sleeves would be even longer.

A soft chinguard protects your face from the zipper
A soft chin guard protects your face from the zipper


The REI’s Merino Midweight Half-Zip Base Layer Top is the kind of shirt you can wear on a multi-day backpacking trip without smelling stinky. (Ask me how I know.) The fabric is soft and not itchy.  Although the sleeves are snug when you first put it on after washing, they loosen up with wear.  The zip neck is pleasantly snug without being tight.  It’s easily washed and cared for with no sign of wear or pilling.  It offers good warmth for its weight.  If you can catch REI Merino base layers on sale, they can be a great deal.

Disclosure: SectionHiker purchased this product for review.

SectionHiker is reader-supported. We only make money if you purchase a product through our affiliate links. Help us continue to test and write unsponsored and independent gear reviews, beginner FAQs, and free hiking guides.


  1. Wanda – my wife is also short and often has to alter the sleeves on any long sleeve outdoor shirts she purchases. In your opinion, since these do not have thumb holes, would it be easy to take up the sleeves?

    Thank you for the review. Always looking for good merino wool based items at a decent price.

    • If you are good with sewing stretchy stuff, they should be very easy to shorten. I’ve yet to shorten stretchy sleeves and have it look professional, so I mostly push them up or roll them up.

  2. Wanda – I own a few of these REI merino shirts too, but unlike you, I don’t follow the washing and drying instructions and dry them with all of my other hiking clothes on high heat. Despite that, mine haven’t shrunk and are still in great shape. Wearing one now as a matter of fact!

Leave a Reply

Your email address will not be published. Required fields are marked *