Both of HP's higher-end ZBooks support a maximum of 32 GB of 1,600-GHz DDR3L dual-channel memory in two or four SODIMM slots, depending on the processor. Both can handle spinning or solid-state drives as large as 1 TB or 512 GB, respectively. The sub-eight pound ZBook 17 can house as many as four internal hard drives. All memory and storage are accessible without tools. For external storage and display, ZBook 15 and 17 both provide three USB 3.0 ports (one with charging) and DisplayPort 1.2 output with 4k support. There's also a Thunderbolt 2 port with 20 GB/s transfer rate for up to six external storage and/or display devices. Both offer a spill-resistant keyboard with bottom drain and comply with the MIL-STD 810G spec for durability and resistance to incursions by sand, dust, moisture and other contaminants. HP said it will offer a 3,200 x 1,800 version of the 6.2-pound ZBook 15. ZBook 15 and ZBook 17 are initially available only with quad-core processors; prices start at $1,899.