Last week the Support Tubes were put in nominal position in readiness for Cartridge Installation.  The iLIGO SEI CAS elements were removed and replaced with HEPI Housings.  This required much craning, wrenching, drilling & tapping, etc.  Monday & Tuesday, the HEPI Actuators were installed, not possible once cleanroom is in place, and final securing of the housings were completed.  The SEI external structure is now ready for the Cartridge.