I have mixed feelings about retractable leads, I do have them for both my dogs but I only use them now when we are beach or field walking. The reason being was I allowed Bella's to get too long on the street one day and she was nearly run over by a car reversing out of a drive, it was totally my fault and I can't believe I was so stupid. I do think they are fine for open areas though. There seems to be two kinds available, one has a thin string like cord and the other has a thicker more tape like cord, I prefer the tape as it appears to be stronger. I got mine from pets at home and I think they were about £14 they can go as expensive as £25.
Willow, Bella & Alfie