This is a Leupold Ring known as the DD, model 49918.
Leupold's trademarked Dual Dovetail(TM) system provides a classic low-profile mount for scopes on a variety of popular actions. Bases accept all Leupold rotary dovetail rings. Dovetail connections at both front and rear provide a rock-solid mounting platform.
Features:
Versatile
2 piece base
Dual dovetail system
