i own one, i don't like them.
1. takes forever to scrape enough magnisium
2. wenn it's not wind still, the scrapped magnisium goes for a walk.
3. dulls my knife
4. not real flame, just bright white flash-ish. Ugly and i find it harder to light things than other tinder.
Take a hacksaw with you to scrape.
make sure something is blocking the wind.
Fatwood is WAY BETER alterative.