These spikes feel light and fit snugly around your shoe. The thin rubber conforms well to lightweight trail shoes, so they don't shift or twist on your foot. You run naturally with them, without the bulky feel of heavier spikes.
They perform best when trails are frozen or snow-covered. Think of a winter trail in the Ardennes, a frosty morning on the Veluwe, or a trek in the Alps where you cross an old snowfield. On a slippery descent, you notice the difference: where you would otherwise shuffle cautiously, you can now simply keep walking and place your foot down with confidence. Because they fold up small, you can easily carry them in your jacket or backpack for the section where you need them.
If in doubt, look at your shoes and the terrain. The spikes are designed for lightweight running and hiking shoes, so they do not fit as well on wide, stiff mountaineering boots. For steep ice or real glacier treks, you need crampons. Walking on bare rock or asphalt is less comfortable and the points wear down faster, so only put them on when it is really slippery.
In short: light grip for trail runners who want to keep running in the winter.
