Where do I find one of these Tell Tale Monitors?

[Jacobsroodt]

We have a crack in a wall and I need to monitor movement.

Does anyone know where to find these locally?


Looking for a Crack Monitoring Record, Standard Tell-Tale Crack Monitor.

 

[Kobus Myburgh]

 

[RobCrouch]

 

[Jacobsroodt]

 

[husky]