bass blockers (caps) and there FREQ

hey i have some caps or bass blockers come ppl call them.. you use then on stock speakers to cut the low end bass out. but i am not sure what FREQ they cut at... the numbers are 50v 470uf. i just got a huge bag of them given to me by a customer.
any one know the cut FREQ or a web site for me to go to so i can find out

 

http://www.the12volt.com/caraudio/crosscalc.asp#ccc

Looks like about 85hz high-pass at 4 ohms, 6db/octave.