An external Maximum Power Point Tracker (MPPT) compatible with Yeti X and Yeti Lithium Power Stations 1000W and up. Recommended for the X line for additional solar input capability for up to 40% faster charge times. NOTE: All Yeti Power Stations feature integrated MPPT charging. Not compatible with X line power supplies, only compatible with Yeti LI power supplies. Usage Note: The Yeti Link Expansion Module and Yeti Lithium MPPT Solar Charging Optimization Module use the same expansion bay, so they are unable to be used at the same time.  Open Box items may look and feel brand new, although packaging may no longer be up to Goal Zero standards to sell as brand new. Products may be unused returns or demo models and no longer have packaging. Product are in good condition and verified to be functional. No Returns or Exchanges. 6 Month Warranty. Additional promos or discounts cannot be applied to the already reduced price.