Can be used w/ factory or flat wound springs Rigid steel body improves lockup w/o "rod flex" Hex screw allows user to choose spring weights Will not chip or crack like plastic guiderods Blue loctite recommended on hex screw threads Can be used w/ gen 4 glocks w/ conversion insert GR-1722 fits G17/17L/22/24/31/34/35/37 pistols GR-1923 fits G19/23/32/38 pistols Mfg: Glockparts.Com