Couple of questions you need to ask the vendor.
What is the NRR?
Who certified the product and the name of the certifying organization?
(note) if he says OSHA approved or NIOSH he does not know what he is doing. Neither OSHA or the National Institute of Occupational Safety and Health (NIOSH) actually approve a product.
Does he provide a certificate?
If he cannot provide the information I would pass.
Should you be unable to utilize the foam plugs for some reason, I would consult an audiologist. They can evaluate your ears and provide you with a professional assessment.
Prior to the invention of the foam plugs, I used the molded plugs for my high hazard employs. They lasted about 2 months and were expensive.