The Sinclair Offset Scope Level has a unique offset design that allows the shooter to see the level while still behind the scope. The offset level attaches to the riflescope like a scope ring and can be positioned so the shooter can see it easily. The Sinclair Scope Level helps the shooter avoid loss of accuracy resulting from positioning (canting) the rifle differently each time.
The machined aluminum Sinclair Offset Scope Level is available for 1 inch and 30 mm scope tubes. Available in matte black and satin silver finishes. The Sinclair Offset Scope Level can be mounted for use by right-hand or left-hand shooters.
Big Book Catalog, Issue:68, Page:300
Sinclair, Issue:5A, Page:211