One issue with them, (specifically the crossnut variety) is if you don't use the correct tool a crossnut might start spinning in the metal. If that ever happens

One issue with them, (specifically the crossnut variety) is if you don't use the correct tool a crossnut might start spinning in the metal. If that ever happens when your final bolt is already in, it's like having a nut on the blind side. You can't unscrew the bolt. Otherwise they are great, just but the right settings tool and drill the right size hole.