V4.x is a fully redesigned lower to replace the older V3.1 Super Lower. The “x” represents the subversion that have not yet been developed. The Naming scheme was also changed to “SL-15”, SL standing for “Super Lower”. The new SL-9 lower will be based off of the V4.x SL-15 lower.
![](https://hoffmantactical.com/wp-content/uploads/2023/11/New-Lower-Right-SIde-1024x1024.jpg)