I got one of those, and couldn't keep it tight, and it came loose 20 miles from home when my kid was riding it. He did not crash, but he was very unhappy with me.

This taught me to buy two things:

(1) A multi-tool, to fix stuff like that 20 miles from home.

(2) One of these:



At least the clown-stem looks better than the adjustable thingie: