"With its patented Reverse Telescopic design, the BeatDown Outdoors Ultimate Shorty Double Stack is the only sonar mount on the market that allows you to position a pair of graphs at any height from the deck of your boat up to 17""H, with just the twist of a knob. This allows you a clear view from any vantage point, whether fishing or cruising, and also enables you to lower the units out of the way for full clearance when flipping or pitching. Locking collars with oversized knobs make for quick, secure adjustments, even when wearing gloves. Crafted of corrosion-resistant 6061 aluminum and 304 stainless steel. Includes an under-deck plate for secure installation. Compatible with Garmin, Humminbird, and Lowrance sonar cradles. Holds 2 sonar units at any height up to 17""H Adjusts with just a quick twist of a knob Provides a clear view from any vantage point Locking collars with oversized knobs Quality 6061 aluminum/304 stainless steel construction Includes an under-deck plate Compatible with Garmin, Humminbird, and LowranceNOTE: Mounting hardware not included."