At Design Energy Group, we supply VARYING size led t8 tube lights.  4' is standard, but we also have 2', 3', 6', and 8' T8 tubes.  

Take a look at these examples below

Internal driven T8 LED, 120/277 Volt, T8 medium G13 bi-pin mounting that integrates energy saving SMD LED technology into a standard T8 fluorescent format.