BRT-058 - Linear Helmet Press Kit with Guides and Zipnut - designed for the installation of all sizes of helmet cups. This kit includes a 3/8 inch (10 mm) Acme thread press for helmet installation, a pair of interchangeable quick grips for liners, a 3/8 quick-release Zipnut, and a complete set of guides to ensure effective and precise helmet installation. The linear helmet press utilizes the same Acme thread design with a 29-degree angle found in high-precision applications such as nut-screws for CNC machines. This design allows for wider and more stable thread bases, providing greater resistance and overall durability. More importantly, this thread design is much more precise than standard V-threads, delivering an exact pressure of 90 degrees for perfect placement and alignment of the bearings. Unlike other available bearing press products that specify a simple socket or no bearing at all, each linear press rod is equipped with a static nut that contains a precision ball bearing to ensure smooth and precise operation without friction. Finally, the linear quick grips function like small transformers, allowing you to combine two short grips for tight spaces, two long grips for more leverage, or long-short grips for better control. These aluminum 6061 grips snap onto the fixed pressure nut and our unique quick-release Zipnut for fast and professional results. Use them by hand, or with adjustable wrenches or nuts, or if you prefer working with Allen keys, this option has also been integrated into the end of each grip.