The Vacextender attachment to the penis is from above the cap that goes over the glans, so this makes the top of the extender 1 1/4" above the top of the glans, maybe more, as the cap does not completely cover the glans. On the strap system, the strap pulls under the glans, so the top of the extender is about even with the tip of the glans. 
After posting yesterday, I put on the extender using the old strap system, and was surprised to see I could add a 1/4" rod extension to each rod, so it seems the vacextender is indeed pulling, and now I think it does a better job than the strap. When you compress the springs with the strap, and reach the maximum pull, the glans slips past the strap, the strap strtetches, and even the strap starts to slide out of the slots in the holder. With the vacextender you can pull well beyond this point, without any slippage, until it is just plain too much. It is comfortable up until the too much point. With the strap, the edges of my glans start to be scrunched up, and stays that way for a while after I remove the extender, with the vaxextender, the part of the glans that fits inside the cap is under vaccum, so that part gets hard and pumped up, but only that part, its kind of weird to have part of the glans hard, and other parts not. 
Again, I wore the around the waist strap, and even wore the extender this way to the gym, and worked out. No one can see it, specially if you leave your shirt out. I did have to go to the bathroom halfway thru my work out, and flip my penis to the other side of my body. While this is not a very hard pull, it has become my favorite alternative use of the extender, and leaves you with a very loose hang when you take it off.