Replacement Fairing Block f/GT21, GT23, GT41, GT50 & GT51 Series of Thru-Hull Scanning Transducers Use our fairing block to position your Garmin GT21, GT23, GT41, GT50 or GT51 series of thru-hull scanning transducers parallel to the water line for increased sonar accuracy. If the deadrise angle of your mounting location exceeds 5 degrees, you should use a fairing block to mount the device. Warning [https://productimageserver.com/prop65/6pt.png]WARNING: This product can expose you to chemicals which are known to the State of California to cause cancer, birth defects or other reproductive harm. For more information go to P65Warnings.ca.gov [http://P65Warnings.ca.gov].