Not very accurate

It works as a gauge and I use it, but it can vary as much as 1/8 of an inch depending on how hard you are pushing on it. That can add up to quite a bit after 20 rows of siding with each row based on the previous. Would be much better, if it were more rigid.

Same item the US Military buys...

All I gotta say is WOW. This is the same item the US Military use to purchase for $1999, at bulk pricing. They have now discount it so average joes like you and me can get the same MilGrade product for our own home use.
I cant believe i saved 99% on this item, I will be stocking up for the winter at prices like this. :>