BackPacks?? What are they?

I have been looking to use Arduino to add functionality to my model train layout. My favourite is a model speedo that calculates and displays the speed of trains passing between two sensors.

See Arduino Your Home & Environment: Arduino Model Railroad Scale Speedometer - Finished for the project.

The project mentions Adafruit 7 segment backpacks.

What are these?

Do I need to use them?

Does Arduino make a similar product?

Thanks
Nippy

Nippy1610:
What are these?

Do I need to use them?

Read this:

then if you have specific questions come back here.

Nippy1610:
Does Arduino make a similar product?

No