Do you know if Expresscard slots in laptop PC's are normally x4 lane capable?

Unfortunately, all laptops only put out PCIe .01 x1 (2.5Gb/s) bandwidth through the ExpressCard slot. We offer a x4 connector on an ExpressCard for customers who want to connect the laptop to a device with a x4 connector. A laptop (Apple, Windows, Acer, to name a few) with Thunderbolt 2 operates at 20Gb/s.