Identification: Is this an 150A fuse? Or something else?
Looks like a crude form of "ANL" style automotive fuse as used in (insane) audio systems and inverters. 

Similar to this (from this website):



It would be used in an individual fuse holder with a (typically transparent) cover on it. As it's intended only for low voltage applications, it probably does not need to meet much in the way of safety standards to be sold.