Spider Coupling - Printrbot Simple Metal

Drop in replacement spider coupling for Printrbot Simple Metal. My Simple Metal came with a flexible helical coupling for the Z axis that would stretch or compress during a print, making the Z axis very inaccurate, and causing uneven layers. After finding out that a flexible helical coupling on the Simple Metal is used for the wrong layout, as it should not have vertical load on the coupler, people recommended a spider coupling instead, as it can support vertical load while still allowing twist