Product review (1 stars): FLIMSY PLASTIC Vent Register = SAFETY HAZARD!!!
This is advertised as being made of durable plastic, but it's cheap, flimsy plastic.  The heater vent I wanted to use this on receives some traffic, and when I installed this, it easily "gave" underfoot.  It didn't break, but it gave a LOT and I didn't put my full weight down on it, since I realized from looking at it that it was cheap plastic.  For my safety (and the safety of everyone else in this house), I removed the register and am back to using the original STRONG metal register that was there to begin with.  This cheap plastic humidifier register is now sitting in its box, safety out of harm's way.  I wish I knew how to return this for a full refund...

In short, STAY AWAY FROM THIS REGISTER if it's going to be put anywhere where people might step on it!