These cables come with the red or blue LEDs aready attached. The black block connector has a "key" on it so that it can only be inserted the correct way.

Package of 12 blue, Catalog #432

Package of 36 blue, Catalog #433

Package of 12 red, Catalog #422

Retail Price:  $36.00

School Price: $30.00

Package of 36 red, Catalog #423

Retail Price:  $99.00

School Price: $80.00

Blue LED Cables

Package of 6 blue, Catalog #431

Package of 6 red, 6 blue, Catalog #434

Package of 18 red + 18 blue, Catalog #435

Combo Red & Blue LED Cable Packages

Package of 3 red, 3 blue, Catalog #433

Package of 6 red, Catalog #421

Retail Price:  $18.00

School Price: $15.00

Red LED Cables

Compare this price for 6 LEDs ($0.42 each) to alternate systems like Hummingbird ($2.95 each - that would be about $35 for one project, 7x more expensive) or LittleBits ($7.95, 19x more expensive).