Fig. 1. Insertion Device Hybrid Permanent Magnet Undulators (HPMU) Superconducting Undulators (SCU) Intermediate-Energy X-ray Undulators (IEX) Electromagnetic Variable Polarizing Undulators (EMVPU) Circularly Polarized Undulator (CPU) Revolvers Insertion Devices by Sector APS Device Installations On-Axis Brilliance Tuning Curves - Existing Undulators On-Axis Brilliance Tuning Curves - Various Lengths