LED Dog Collar, USB Rechargeable Light Up Dog Collar, TPU Cuttable Glowing Pet Safety Collar for Nighttime Dog Walking (Blue)

I love the collar, but my dog has outgrown it and it's getting tight. I only need to replace the collar, not the mechanism. Is that possible?

how long does it stay lit on continuous setting?

Is this collar waterproof? It says it is in the description but I'm not finding anymore information that it truly is waterproof

How do you know when it’s finished charging?