Topeak E-Xplorer Trunk Bag - With MTX QuickTrack 2 Mount - 26L Black. The E-Xplorer Trunk Bag is an ebike specific spare battery carrier made of expanded polypropylene providing excellent impact absorption water resistance high strength and thermal insulation. The grip straps secure your spare battery in place. Compatible with Topeak’s MTX QuickTrack 2.0 system there’s even enough room to carry additional food drink and gear for your eMTB adventures.