Discoverd these two devices while looking for items that would help with my
work on the garden railway that I own.

The thing that caught my eye about these is that they are both designed for 
the sighted but can be accessed by blind or low visioned without modification.

Both items are bluetooth enabled and can be access via an app on both Android 
and Apple smart devices using their in built access software.

Both devices require batteries.

I've tested them on a Samsung S21 running ~~Android 13 and  Samsung S23 running  
Android 14.

More to add when I've used them for a while.
Simple to use, powers on via app on your smart device.
Reads angle by degree, accurate to .5 degree.
Is magnetic so can be attached to blades to ensure vertical cuts etc.
This unit is approx 70 X 70 X 30mm
Requires a single AAA battery
The unit reads off the degrees as you move the two arms apart,

Requires a coin cell battery - thinkit's a CR2032 but double check!
various readings possible - simple and useful.