Perfect Multi-slot Rail Sections: Available in 5-slot 7-slot 13-slot 3 lengths for choose, which can meet different need. 5-slots size: 2.4x0.78x0.31 inch 7-slots size: 3x0.78x0.31 inch 13-slots size: 5.4x0.78x0.31 inch, includes 7 screws, give free extra set of 1 screws and t-nuts. Durable Material: Made with aluminum material, light weight material, solid & durable precision machined out of premium 6061 aircraft aluminum alloy & high strength steel in black matte anodizing finish more suatible for your outdoor hunting and offer durable safe performance in the field. Easy To Install: Install these screws by come with allen wrench tool, simple to install or remove. Notice: Please feel free to email our customer service if you have any question or dissafaction about our rail base mount, our customer service will help you to solve the problem as soon as possible.