Unfortunately, the device as internal installation (LM 30) gave only inaccurate values (sample in the water bag). In contrast to the test measurement on the free water surface is missing about 60% of the water depth or the display jumped or showed no value. Moreover, it seems to be an unbeatable cheap device. The durability and reliability should still show.
With the NASA CRUISER system, I have replaced an echo sounder of the same type. As long as the previous system worked, I was satisfied with it. Unfortunately, the electronics of the first device already after less than 3 years (the boat was not in the water for 2 years) stopped the function. The sonar was still programmable, but showed no depth. Since I had a replacement ultrasound generator, I could exclude donors as a source of error. The new device now works well with the "old" sensor, and I hope that this system will do its service longer than the previous one.
This equipment was intended to replace a Raymarine ST40 sounder, mounted inside the polyester hull in a sealed tube filled with castor oil, as for the Raymarine The Nasa Cruiser displaying fancy data, I removed it