Both versions now in stock at Airsoft Buddy... "WE launched their first open bolt (open chamber) system kit for Gas Blow Back PDW. This kit can replace all tube brass that is using on the GBB PDW. It comes with the inner barrel with new design Hop-Up system. It's more easy to adjust the hop-up like AEGs. Now Standard Barrel Version and Short Barrel Version are available.

For more details, please refer to the following link and images:

WE Gas Blow Back PDW Open Chamber System Kit - Standard

WE Gas Blow Back PDW Open Chamber System Kit - Short

Thanks,

Airsoft Buddy