The Ronstan 2:1 bridle is a little bit better running than the Harken 2:1 bridle. Ultimately there is no difference. The important thing is that you have a 2:1 bridle and sheets for the jib. The bridle attaches blocks to the jib, which you can run the jib sheet through. This gives you purchase on the jib and makes it easier to pull in when sailing in breeze.