This is for a appendix inside the waistband sidecar style holster, these are built with a strip of nylon inbetween them to keep them flexible yet strong. The magazine sides come with a magazine retention device that can fit miltiple different mag sizes. 
 
This holster can be built for these firearms listed below:
 
Glock 19,17,45,34, 23,32
Glock 19,17,34,23, 32 with Surefire X300 A/B
Glock 19,17,34,23,32 with Streamlight TLR1
Glock 48 MOS, 43X MOS with tlr7 sub
Canik TP9/ Mete SFX/SFT, TP9 models
Canik TP9/ Mete SFX/SFT, TP9 with Streamlight TLR1.
Sig P365/365 XL
Sig P320/X5 Legion
Sig P320/X5 Legion with Streamlight TLR1
M&P Shield 9
Sig P226/220 with Streamlight TLR1
FNX- 45 Tactical with Streamlight TLR1
Most 2011's with the Surefire X300