This mounting bracket is for the switch that comes with the motor generator combination from AliExpress.  The motor generator generates DC voltage at 8kW to power an electric golf cart and make it into a hybrid.  It may also enable EV's to have an auxiliary generator.  The motor generator has a little paddle switch that has an ON-Auto-OFF position and snaps into a 19mm hole with a locating rib at 90 degrees.

https://www.aliexpress.us/item/3256809244476496.html?spm=a2g0o.order_list.order_list_main.10.23dc1802FSVFAH&gatewayAdapt=glo2usa