They grip quite tightly and yes, as other users have said, on an 18 it requires a lot of finger strength to hold. The downside, however, is that the spring pops out with the slightest movement and it's so tight that it's dangerous. They were immediately thrown away to avoid getting hurt or causing any serious damage.

It requires two people to be able to assemble the product, one to pull back the cord and the other to insert the pieces that need to be held together. It is very difficult to do it alone.