I don't review things with an angry mind.  That being said, I am prepared to be fair.

These bow biters are not like the ones I had as a kid, these are mechanically functioned with a VERY low level spring. This is not as strong as the locking bow biters I had as a kid. I assume this change is to keep fingers from getting bit.

I bought these for my autistic 4 YR old, and in 6 months, she has only broken one pair.  So the plastic is fairly durable.  They do keep her shoes tied, I don't suggest double knots, they might be too fat for the bow biter to swallow.

If your child is into untying their shoes, they are just curious, I don't see that as a reason to knock the product.  These work just fine for holding a bow in place, and make a great little shoe accessory for your little one to look at on their feet!