A strainer for a snare assembly adapted to be attached to a percussion instrument, comprising a tensioning mechanism for applying a tension to snares of a percussion instrument; a lever having a first end and a second end, the lever being pivotably mounted to the tensioning mechanism, whereby pivoting the lever changes a position of the tensioning mechanism to change the tension in the snares; and a positive locking mechanism to positively lock said lever in at least one of a plurality of snare tensioning positions. The positive lock mechanism mechanically connects the lever to a body portion fixedly mounted to the percussion instrument. In the preferred embodiment, the positive locking mechanism comprises a movable button that is movable relative to the lever to change the positive locking mechanism to an unlocking condition where the lever is free to pivot with respect to the body portion.