If you already have a cyclocomputer, I would recommend the F6. I have one and it has more features than the f4(which is a women's model, smaller wrist unit) and can be had for $99 at sports authority, dick's, etc. Don't overpay at the LBS if you don't have to.

http://www.dickssportinggoods.com/pr...earchId=851740

specs on f4(WOMEN'S MODEL)
http://polarusa.com/products/fseries/f4.asp

specs on F6
http://polarusa.com/products/fseries...p?cat=consumer