I've worn Acto Pro by Oticon for two years now ,even at $2200 each, with $100 each custom molded inserts they are not safe to use as hearing protection the simple reason being the inserts are vented. I can shut the mics off but sound still enters the vented ear piece. Going out on a limb here but anything worn in the ear canal for extended periods will have to have vents if for nothing more than moisture ventilation.