PRK is short for Pack Rifle Kit. The PRK converts your Crickett or Chipmunk youth rifle into a light weight, take down pack rifle. The PRK replaces the barrel and stock of of your Crickett or Chipmunk rifle with light weight alternatives, shaving 1 pound 10 ounces out of the OEM version. The barrel is constructed of a carbon fiber outer, with aluminum components joining the carbon fiber outer to the Cro-Moly steel, button rifled barrel liner. The carbon fiber tube stock is simple and functional, it is made of carbon fiber and aluminum tube. The stock is hollow, with an ID of .875 Inches by 11 Inches deep for storage. The PRK has 13-5/8 Inch length of pull for adult frames. We recommend having a gunsmith install the PRK, but for those of you that are mechanically inclined, it is relatively simple. This is a Kit that consists of a barrel and a stock, it is not a complete rifle. You have to provide a Crickett or Chipmunk rifle to put this kit on.