This is the factory GLOCK 9mm barrel that comes stock in the Glock model 34. It can also be used to convert the 17C to shoot as a non-compensated as an extended barrel. Using it to convert the 35 to shoot 9mm is not recommended and unsafe as it is not a 100% fit. This barrel will not work extended in the 19 or 26 due to the difference in the locking blocks. You can use it as an extended barrel in the Glock 17.