Never thought I would leave reviews, but here we go.I have purchased this laser as the price is well bellow the comparable at home depot,lowes etc....And I purchased other vevor products and they didn't disappoint (if I had any issues with shipping or the products costumer service was outstanding).In particular I bought the laser as I originally had a bosch(700$)and was not happy with it.So I gave this a try and am glad I did .I am building a barndominium with a concreteless slab and so I had to screed a lot of dirt and rock to get it nice and flat and the laser was my friend .I did over 1600sqft and it grade it perfect,and if there was any errors would have been on my side not the laser.I attach a pic with the finished subfloor. I haven't tested all the features of thus grading laser but I can tell you one thing :this has a battery that is rechargeable and it last me all day ,not sure how long it lasts as I was charging it at the end of the day so I don't run out of power the next day .I recommend this and other products from vevor .You have to think that now everything is made in China, even the good products and this is one of them.This is not a paid review I paid money for the laser it is not sponsored .