The usage of this Recoil spring guide rod with a Generation 4 slide will require the purchase of a reducing ring (RDC-4G-SS-DLC or RDC-4G-SS)
1st-3rd Gen
• Glock 20
• Glock 20C
• Glock 20S
• Glock 21
• Glock 21C
• Glock 21S
4th Gen
• Glock 20
• Glock 21
• Glock 40
• Glock 41