I also recommend getting one stronger than you supposedly need.
And using it with a Premier EasyWalk harness (got mine from Amazon, on advice from my SIL, the dog behaviourist). It makes walking a young, lively dog, who forgets her good manners whenever something runs across in front of her, a much more pleasant process.
A harness is a good thing with a retractable lead, or there is the risk of them running to the length of the lead and then being pulled short, with all that force on their neck collar. However some harnesses encourage pulling.
The attachment ring is at the front of these harnesses, on purpose, so instead of allowing them to pull like sled dogs, it turns them round if they pull hard, so they stop trying to.