Acoupower

I don’t want to go get a good decimal reader to see how loud mine and some of my friends car audio systems are, but I don’t want to go to a professional place and pay for each one, ive seen db readers like, Scosche SPL1000F 135DB Max Spl Meter, for cheap, but I don’t know if this is a good one or if there is a better one, any suggestions on one?

the scosche meter is junk.do not buy it.i saw one of those put into a couple of cars at a stereo competition.the real db meter read 144.5 db, the scosche read 122.7 db.then in another car the real meter said 137.3 and the scosche said 129.7 db.totally useless.