Little clamps to locate your glass bed in the XY axis'. Per clamp, you'll need: Your bed does need to be disassembled to install this, as the clamp is bolted into place through the riser bolts that hold the bed to the Y carriage. If you've made the (highly recommended) M3 nyloc nut mod to the bed levelling bolts, they are used to secure the clamp in the Z axis. If not, use the levelling spring, but it may wear as it is tightened and loosened over time. I also recommend you print this in ABS, due to thermal properties and to avoid warping when your bed gets to temp.