Whole plastic tube case outside + Aluminum groove inside. Much safer than the regular aluminum case outside for high voltage.
Driver removable easily. Driver is the most damageable part among the components of tube. So it just needs to change the driver to a new one when a tube is broken. More cost saved and be on maintenance easily.
Driver is placed inside insulation lamp holder which is on side of tube. Avoid the power wire contact the heat dissipation of aluminum base. Lifetime of driver becomes longer. Accordingly Lifetime of tube becomes longer.