Ergodyne - EGO12209 Chill-Its 6240 Phase Change Cooling Vest Elastic Extenders provide a 3-1/2" extension to the Chill-Its Phase Change Vests (excluding lightweight vests) to increase their size. They are made of 100 percent elastic with hook-and-loop extenders to attach to the vests. These extenders help workers stay cooler, safer and more productive on the job when they need to wear cooling vests that don't quite fit.