I carry a Silvia mirror sighting compass. It is lightweight (about an ounce) and pretty accurate. It is liquid damped and prone to bubbles at altitude but still works. I don't recall the model number but REI carries them. I also carry a spirit-in-glass thermometer that I bought 40 years ago when I was doing field research. It is accurate to the nearest degree, has a protective aluminum cover and it weighs 0.7 oz. i bought it at VanWaters and Rogers and they still stock them. I usually rely on my map if I need to know the altitude although I can read altitude from my Inreach if I need to. The barometer I class in the "too much information" category. I've never felt the need for a barometer while backpacking even though I have a Thommen Everest I used for field work that had a barometer function.