WOW! 5$ not a sale, not stealing - you've invented a whole new category for dealing - I only wish there was a term for it!
It should be held together with residual magnetism. that is good... Prevents swarf from getting in...
-- and now you know how to set an angle. You can use an angle block, or a sin bar to create the angle. You can re-calibrate it with a parallel under the pins and taking a skim pass. I haven't seen one in 20 years but it is a fantastic accessory to your grinder. I bought a 2 axis magnetic sine plate last year so I'm good, but that is a very useful piece of equipment....