How to use: place the scope spirit level on the top scope cap and the action spirit level above the bolt. Once the leveling scale indicates a leveling area, simply tighten the rings. Easy to use and compact size for convenient storage and transport. The bubble for the shell is made of acrylic and is designed for levelling scopes. Compact: The bubble for bowl is made of acrylic and plastic, easy to use and compact size for convenient storage. Accuracy: with to ensure crosshairs are aligned to allow correct placement and reliable doping settings. With strong magnet at the bottom for easy hands-free use., Manufacturer: she1qi_cxy