KwikLift

You drive car up on ramps, put wheel chocks in place then, as the gentlemen said you use a floor jack under the rear bar, jack the ramps up then flip the back legs down and lock them in place. It's pretty slick, I believe there about 20 inches which is nice with a creeper and you can reach everything under the car with ease while on your back and still have clearance.
Thanks for the compliments on 64, it is a 20 footer. Has some paint flaws the quarters have some waving in them but it is solid. Has a mid 80's 318 in it with the push button tranny. Lot of fun, put over 3000 miles on last summer, gotta go though. Going from a five car to 3 car and keeping the 68 Dart GT ragtop, clearing out stuff.
The ramps slide apart, which allows you to move them around if needed. I brought mine home in back of S-10 pick-up, then assembled. There not light but it's do-able.