Groco Spanner Wrench/Deck Plate Kit Groco strainers ARG, and SS have three holes in strainer cap which allow for use of a spanner wrench to tighten or loosen the cover before or after maintenance. Hand-tight is sufficient for a good seal but some boaters may prefer to "snug" the cover, or "break the seal: when servicing with the aid of this wrench. Cast bronze with 1/4" diameter stainless steel pins on one side and 5/16" pins on the other side. Opens to fit deck plates and strainer covers with key holes up to 7" apart. Hole in the handle makes it easy to hang the wrench in a location convenient to strainer location.