I purchased a model like this for an older 500HF system and this model for my Viper 791XV. My battery died one night in a downtown parking garage. I was very confident the backup system would do exactly what I needed it for. A few cars were broken into that night, but my truck was not touched.

Easy to install , a must for any alarm system. do not waste $500.00 on security system, and some low life all he has to do is to cut your battery wires , that's when this product kicks in.