New Nozzle Height detector?

Any idea what this product is?

https://shop.tiertime.com/product/nozzle-height-detector-china-stock/

is listed as compatible with many printers.

Looks to me like and aid for manual calibration or something…

Used to set the nozzle height. Twotrees Sapphire use the same.

Looks cool - just keep lowering the nozzle until the light switches on. Clever idea… Now if only Tiertime could rewrite the servo channel to do something useful… Like opening and closing the vent after the raft is printed. That would actually be useful.