This is 4" long.
It is between 1.25 and 1.5 inches from the rail downward, if that is what you mean by height, depending on whether you need to add a piece of picatinny rail to connect to your handguard or not.
This is 4" long.
It is between 1.25 and 1.5 inches from the rail downward, if that is what you mean by height, depending on whether you need to add a piece of picatinny rail to connect to your handguard or not.