There ya go @harpo75!
VSS offers the double sleeve in a variety of different configurations. I recommend getting one packet (25 sleeves)---or even just a single sleeve---of each model that looks interesting, to learn what works best for you (there is also a $5 sample pack). For instance, the Double Pocket sleeve has a flap that encloses the outer cover, and you have a choice of a flap with no tape (just tuck in the flap), a flap with a strip of tape on it, and also a version with the strip of tape on the body of the sleeve rather than the flap.
For single-LP gatefold jackets, VSS offers a "Multifunctional" model, which you use in conjunction with the Double Pocket model (for reasons which will become apparent when you put them on, it must be the Double Pocket with the tape strip on the body, not the flap). There is also a double-LP gatefold model, or you can do what I have done and just use two regular Double Pocket sleeves.
The standard sized sleeve is about 12-5/8" (+ or - a coupla millimeters) tall and deep, but there are also 12-3/4" and 13" versions available (for MoFi and Analogue Productions-sized covers). VSS also offers plain old single pocket outer sleeves (with or without a flap), and inner sleeves as well. At least as good as the MoFi sleeves (VSS offers a thicker version), and cheaper.
Orders of $55 or greater (U.S.A. dollars) ship free. And I may as well get this out of the way: No, I am not on the VSS payroll.