Anybody taken a look at these? What makes them different than the swivel style weight jacks you can get at speedway?

 

It's a bottom up, rather than top down solution. Both are swivel.
Speedway is top down - weld in plate in spring cup (k-member), and turn bolt from the top. Much cheaper, much more work, not reversible (unless you buy another k-member).
DSE is bottom up - plate fits in their a-arms, and you turn the bolt from below the a-arm. No cutting or welding means it is reversible. BUT, you have to have their a-arms, too. Expensive, but if you ever sell the car, you could replace with stock a-arms, then sell the DSE parts to gain back some expense.

 

Thanks for the reply. Looking at the pdf instructions on detroit speed, you don't need their a-arms.