Backer levels that are labeled "Eligible for addons" can have additional Flickerstrips and extensions added on to them. To do this, you'll need to do some math.
First, take the base pledge level for the tier you've chose.. eg. $209 for the "mobile kit".
Then, decide which addons you want to add to your order. These can be either Flickerstrip units with the controller and a 10ft strip or addon units for 6ft that can be "daisy chained" from one controller. For example, say I want 1 additional Flickerstrip and 1 additional extension.
For each additional Flickerstrip, add $80 to your pledge.
For each additional extension, add $25 to your pledge.
In this example, $209 + $80 + $25 = $314
Finally, don't forget to add any shipping costs if you're located outside of the US.
Once you've gotten a final number, simply enter that as your "Pledge Amount" as you check out. We'll double check with anyone who has pledged more than their tier amount to make sure that we deliver the right rewards.