This is a mount for depth gauge.
It is very useful to fine tune the bed leveling and planarity.
The mount is designed for this depth gauge:
https://www.banggood.com/Auto-Digital-Tire-Tread-Depth-Gauge-0-25_4mm-Measurer-Tool-Caliper-p-1428018.html?rmmds=search&ID=224&cur_warehouse=CN
Ender_3_Gauge_Mount.stl | 464.6KB |