The Personna Lab Blue 5 pack I bough had blades marked like those in your link, but the 100 pack ones have different markings.
Instead of simply having 4 arrows, the 100 pack blades Say "Personna Super" and "Personna Made in U.S.A" on the top and
bottom of each side of the blade.
As jdjones mentioned, these are labs. I recently ordered a sample of Treet dura-sharps from ebay, and the seller included one of these blades in the package. So far, I've tried it in a LC NEW, 40s superspeed, and a R89. I was impressed enough that I ordered 100 more. I've never used a Med Prep blade, so I can't make any comparison there. Like dharasick said, $13/100 is a pretty good price.
I received my first packs of Med Preps and Israeli Reds a few days ago.
Yesterday, I loaded a Med Prep into my Joris Palladium and got myself a BBS shave. No cuts, no weepers. There was a bit of irritation, but I always get that with my Joris and other aggressive razors. Today was a bigger test - a Med Prep in my Merkur Vision, with the gap set wide open. Same results. In my mind, these are very close in quality and sharpness to Feathers, at a much lower price. The Astra SP's give me a more comfortable shave, but it's never as close as a Feather. Hmmm....what about tomorrow? The R41, maybe? Or the FaTip? We shall see....
I tried these yesterday (5-pack from WCS) and half way through the shave I switched to Gillette 7am yellows.
I so far tried Merkur, Wilkinson, Feather, Astra and the yellows. These ones were my least favorite.
I usually start with the Merkur Progress @1 so it does require a very sharp blade to work properly. I might give them a second try down the road just for good measure.
After getting very good results in two aggressive razors (Merkur Vision and Joris Palladium), I tried one yesterday in my (very mild) Jagger Barley and had an excellent shave. I think it's in the upper echelon in both sharpness and comfort. Having said that, I think I'd still prefer a Feather in mild razors, but in really aggressive razors (I'll have to try it in my R41), I think it's a very good choice.
Finally got around trying my first Personna Lab, took one out of the little paper box where it was squeezed in with 99 other blades. Removed the blue paper, and loaded in into the Fat Boy dialed at 5. Well, a very satisfactory shave, very sharp and smooth, a perfect shave with no nicks or cuts. It was indeed a very good buy. Will try in other razors now too over the next few days.