Start with the 150 when you want a lighter base top beneath a flexible layer system. Investigate the 260 when a heavier top and its length suit the way you dress. These are choices about your starting layer, not two temperature ratings.
What the selected listings establish
| Decision point | XKG Foundation 150 Merino 1/4 Zip | XKG Foundation 260 Merino 1/4 Zip |
|---|---|---|
| Current blend | 90% merino wool, 10% nylon | 90% merino wool, 10% nylon |
| Manufacturer class | 150; manufacturer class, area basis not stated | 260; manufacturer class, area basis not stated |
| Neck opening | Quarter zip | Quarter zip |
| Listed garment mass | 7.8 oz | 10.8 oz |
| Measurement basis | Manufacturer listed; size and measurement conditions not specified | Manufacturer listed; size and measurement conditions not specified |
The 150 and 260 descriptions do not supply matched thermal tests. A higher model number cannot tell you whether you will overheat on the climb or stay comfortable during a stop.
Two owner questions change the choice
The lighter top raises a coverage question: Brian wanted a hood. The heavier top raises a storage question: Hyer reported a pocket attachment problem. Decide which feature matters before comparing the garment weights.
Try each beneath the same outer layer. Compare neck bulk, sleeve movement and tuck length; leave the rest of the outfit unchanged. If both collars are awkward, investigate the 150 hoodie instead of treating this pair as the only choices.
