I was surprised at how accurate and sensitive these levels are. I compared them to a very sensitive driver level and they were perfectly level and could detect very small level changes (not as sensitive as the driver level but very well). These spirit levels are easy to read and small enough to fit in tight spaces. . I was able to stick on an old camera tripod that had lost its bladder. They do not come with any type of "glue" or tape. I'd say that makes them more useful as I've used the 'stick' type in the past and the duct tape made it out of the layer. With them you have the option of using thick cement and rocking them horizontally before the glue sets.