355 CV boot clamp replacement?

What is the preferred CV boot clamp brand and type for a 355?

My boots / clamps were near new when I bought the car but the boots have since partially collapsed (in less than a year) from an apparent partial vacuum inside. They are still supple and appear in good shape, just partially sucked in now. Don't know why this has occurred. Seems odd. Others on Fchat have suggested a permanent vent hole but I'm reluctant to make a permanent opening, regardless of how small, that might let grease leak out. To correct the problem, I plan to remove the small clamp, let some air back in and put on a new clamp (I'm assuming the old clamp can't be reused....its not a worm gear type). I'm not familiar with the type clamps that are on the car now so I'm asking for advice from you guys before I start this.