The LP detector is exactly whay I ordered. That is to say....I needed a replacement for the unit in my RV, and this was an exact fit. At the beginning of the season, I connected the batteries in my RV and the alarm started sounding. The color of the LED light indicated that the unit needed to be replaced. So I did some searching and found out that the alarm is supposed to be replaced every 5 years....This was year 12 with this RV. The unit is an exact fit/replacement for what I had. Simple to connect, only two wires (of course the wire colors do not match the wires in the RV, so be sure to compare the old and new units before you make those connections).