What is the best hair care product to volumize (or give a fuller appearance) to a man's thinnin

Mousse or hairspray if it's used right. Stay away from gels or pomades that may weigh hair down.

Volumizing shampoos work as well - if you can't find "mens" products it doesn't matter - it's just women's products in a grey bottle (I used to work in skin care and know this as a fact - they market it to you in grey packaging so you feel more comfortable buying it, but it's the same thing).

What is the best hair care product to volumize (or give a fuller appearance) to a man's thinning hair?

or you could bic it, then you dont have to worry about it.

balding man = not so hot

bald man = not too shabby (unless you have a mishapen head)