SunBlaster T5HO lighting kits and combos come in standard in 2' 3' and 4' lengths, these are the most poplar sizes. You may have a custom application that you would like to have a continuous run of lighting, not interrupted by a linking cord. That's where SunBlaster's Solid Link connectors come in. Use the Solid Link connectors between two 4' SunBlaster T5's and you now have an 8' T5, add another and you have 12', add another 16' and so on. Remember you can link up to and including 8 SunBlaster T5HO lighting kits or Combo's form a single power source.