Do those phiten necklaces that sports players wear really work? it is said to have health benefits on the companies website. is it snake oil?

Not enough evidence: There is some science to support that titanium microparticle-permeated tape in contact with skin over injuries can speed healing, but I see no evidence the necklaces have benefits- see http://www.mdpi.com/2079-4983/5/1/1 This doesn't mean it won't help, just not sufficient evidence to tell. By the way, snake oil is a rich source of omega 3 essential fatty acids so likely had real health benefits!