The MH-26a is a battery charger specifically designed to charge up to two EN-EL18a or EN-EL18 Li-ion batteries. It is a supplied accessory for the D4S D-SLR camera and comes with a power cable and two contact protectors.
The MH-26a battery charger comes with the D4S D-SLR. It is not available for sale as a replacement item. If you want to replace your MH-26a.