Deborah, you are not wrong. The Hercules HA300 will not hold an SP3. I just bought an SP3 and already owned the HA300 that I'd used with an iPad. HA300 may work for other Surface models...? I don't know the size of the Surfaces that preceded the SP3. Earlier in this string, PhilBiker posted a link to a mount that will work. I'm hoping to find something that has something under the tablet when it's in portrait orientation. The iKlip grabs the device on its long sides. In portrait, nothing is there to prevent it from sliding out. I don't know how tight the grip is.