The primary difference today from the user standpoint is that the Poseidon Se7en+ electronics module has been updated to include native support for Poseidon's optional Solid State Oxygen Sensor. Due to improvements in gas injection the Se7en+ design now requires three instead of four solenoids, theoretically improving reliability by reducing parts count. There also are some internal differences that make the e-module easier to manufacture, assemble and service at the factory. Support for granular absorbent (in the form of a self-pack cartridge) is also now included as standard on the Se7en+ model, as the pre-pack cartridge has been discontinued.