Water Log Series, H-3553T-15-I-D, Compact Combo Bubbler an Xylem Brand.
Model: H-3553T-15-I-D
S/N: 15J101631
Rev: A
Output: SDI-12, 4-20mA, RS-232
Input: 10 to 16 VDC
Last Inspected 10/2015 and passed. Selling as parts, because I no longer have a way to test the unit.