WARNING: Do not use them. After a problem developed with my Raymarine sonar unit, I retained the services of Andreas Di Paolo from Aquatronics International, who came to my boat to diagnose the problem. He was unable to find the problem, but recommended he remove the L-1250 and DSM 300 to futher examin them at his shop. He sent the DSM to Raymarine, who returned it claiming there was nothing wrong with it. Mr. Di Paolo reinstalled both components, then told me I needed a new transducer. The bill was $525.00, with no solution. The estimated cost to replace the transducer was $600.00, but I did not go forward with his recommendation. Upon examining the problem myself with telephone assistance from Raymarine technical support, the problem turned out to be a bad cable connecting the DSM and the display. I replaced the cable for $42.00, and the unit is working properly. It should be apparent to each reader Di Paolo doesn't know what he's doing at great expense to his customers.