This rigidity combined with the shut-loop spindle Manage also allows GG3-S to cut tougher steels, which include stainless (connection to turner's cube) and perhaps tool steels. This physique kit comes regular on Every single GG3-S; current GG3 machines are eligible for an upgrade program. PLEASE Be aware: 80% lowers, frames, https://ghostgunsofficial.com/product-category/gg-purchase-product/