New style Spring Loaded Bearings (SLB) used in all current issue 40 S&W, 357 Sig and 45 GAP Finger Grip & Rail (FGR) frames. The SLB 3439 is shorter than the original SLB and cannot be used with the old style extractors.
MUST be used with new style Loaded Chamber Indicator.
40 S&W & 357 Sig extractor 1899 uses SLB 3439.
45 GAP extractor 1902 uses SLB 3439.
Part number 7 on the schematic.