Anyone using these hit indicators from Hornady?

Anyone using these hit indicators?

0014919_hit-target-impact-indicator.jpg


Instead of a bell I bought a pair (< $20 for two) of these hit indicators from Hornady to attach to a spinner target.

I like that I can use any contact target size I want and have instant visual feedback of a hit. Figure that they will be ideal for my 100 yard spinners.

 
What if you hit the stand?
I get why they are cheap...you'll probably shoot it
The indicator is quite sensitive to an impact transmitted through a support attached to the target so it could be positioned a safe distance from the target where it's not like to be hit.

I got the indicators just before the winter set in so I haven't had much time to test what works and what doesn't.