Milled from .250" (6.35mm) 5083 alloy cast aluminum alloy tool plate. Cast tool plate is very flat, and the casting process means fewer internal stresses which can cause warping. Once machining is complete, these beds are probed with a Renishaw probe on a Haas VF5 mill, and we share this data with you in the form of a "birth certificate", see example below:

The top of the heated bed features a recessed thermistor channel and three attachment points to connect to the Z-yokes. The 9 high temperature neodymium magnets N48SH are recessed into custom milled pockets on the top side of the bed, to keep them as close to the flex sheet as possible.  These magnets are rated for temperatures up to 150 degrees C. They each have a pulling force of 11lbs. They are attached with countersunk screws  

With the Subtle Designs EverFlex sheets, we see holding power in excess of 9 pounds of lateral force. Do note that flex sheets vary in magnetic strength, depending on the material and thickness used by the flex sheet manufacturer.

The magnets will likely cause interference with the bed probes. If using a BLTouch, please use the plastic tipped BLtouch bed leveling probe, and avoid probing directly over the magnets.

Update to the beds as of 3/1/2021: The thermistor channel is now 40mm long instead of to the middle of the bed. This is a change approved by Railcore Labs