Got this to fit on my MSA V Guard 500 hard cap with ease. I was concerned about the ear cup size since I got large ears (2 and 3/4 inches - 6 and 1/2 cm estimate). Well, ear lub does stick out, some adjustment needed to cover it.
Comfortable and noise reduction are as described. Better than my previous ear muffs that gave me headaches within 1-2 hours of use.