I struggled with double unders for almost two years until I tried the Cyclone Speed Rope. The Cyclone Speed Rope is durable, light weight, and fast. This rope has truly helped me overcome the obstacles I was having with double unders. The rope doesn't kink up during storage in your gym bag like other ropes do. I discovered the Cycle Speed Rope during the Crossfit North Central Regionals and haven't looked back since. I also met the owner during regionals and was impressed at how and why he started the company. The company was great to work with after I messed up my cable and sent me a new one without any problem. Definitely would recommend the Cycle Speed Rope or any other products from this company.
Mandy Santiago, http://www.amazon.com/gp/pdp/profile/A34QDOE03R4DOY/ref=cm_cr_dp_pdp