The MBH houses either Sondex or Panex style battery packs. The standard Sondex pack of 5 lithium “C” cells is used in a holder with a one piece housing and top-sub.However, the holder for alkaline cells uses an alternative top-sub and housing that allows longer packs to be used (for example, 10 x C). The top-sub acts as the connection to the slickline cable and can be supplied with various fishing neck profiles. The bottom-sub screws directly into a tool memory section usually creating time “zero” as the tool powers up. There is a protective pressure-isolation barrier between the battery pack and the memory tool below it.