Junk. You'd be better off with a snorkel and a piece of rope.
Cabelas has a ton of portable graphs.
Lol, speaking of snorkels, anyone ever jumped in with one on and checked out the fishes?
This past summer when it was stupid hot out my friend and I would take turn spotting Smallies, pretty cool to see them take a bait and fight under water
Haven't tried one. After being burnt on the many brand name portables, I'm certainly not investing in this.
Though expensive, I tell you what does work, the Hummingbird concept. You buy a Hummingbird then the two lantern battery box and stopper transducer. Its compact, in its own case, and you simply slap the stopper on the bottom of your hull when needed. It won't stay on while underway except at idle, trolling speed.
I use that on my canoe and on my big boat after anchoring or simply idling looking for good spots. On the big boat, I use the standard depth finder for cruising.
Its not cheap but it works.
I still have one of those cast the sensor out things somewhere. It just didn't work.