These antennas provided little if any noticeable improvement in my situation, if you're looking for a significant improvement in your wireless range I recommend using either one of the wireless repeaters (good) or power line wireless extenders (better) solutions. The price is higher but you'll get a measurable improvement in range. I now use all 3 devices and if you're interested in my experience, read on.
I was looking to extend my wireless LAN range to support the growing amount of wireless stuff I'm accumulating in my house, I also wanted to extend a good-enough wireless signal to a detached garage to use a wireless security camera there. Not wanting to spend any more money than necessary I started off with these antennas to see what they'd do for me.
I don't have a way to measure signal quality/performance other than the number of bars on my mobile devices and the internet performance sites like MySpeed but using those tools I could see little if any boost in performance. Apparently I don't really understand radio signal power measures because I thought changing from the 3dBi antenna the router came with to a 9 dBi antenna would more than double my signal power but, again, that higher signal power didn't show up in terms of signal bars on my mobile devices or higher download bandwidth.
I still use the antennas because they "might" be providing marginally more signal power and they were cheap enough that it wasn't worth the bother of returning them.
My next step was to try a wireless repeater, in my case I bought a refurbished Linksys model to go with my Linksys router. This thing did provide a measurable boost in performance inside my house but it's still limited. It can only provide a good signal boost if it receives a reasonably strong signal itself, which limits how far it can be located from the wireless router. And, back to the antenna topic, it uses an internal antenna so the transmitted/repeated signal doesn't reach as far as say a routers signal would.
I've also read that some wireless repeaters hog bandwidth for their communication with the router but I didn't notice this, my performance wasn't affected. However, even though I located both the wireless router (first floor) and repeater (2nd floor) near the outside wall that faces my detached garage I wasn't able to get a good enough signal in the garage to get the wireless cameras to work.
So, my bottom line on the wireless repeaters is they work better than the antennas to extend your signal but performance is somewhat limited so it really depends on your personal situation as to whether it'll solve your range problems. If you strategically locate the router and the repeater you can do OK in an average size house. In my case, my house is 2 story and roughly 3000 square feet and I get pretty good wireless throughout the house with router plus repeater, but, again, very poor signal power in the garage.
My 3rd step was to try a wireless extender using the power line. I bought the T link product based largely on price. For these you connect a base station to your router using an Ethernet cord and then plug the base into a nearby wall outlet. That basically transmits your wireless signal over all the electrical wiring on your property. You can then plug remote units into any outlet in your electrical system, so long as it's on the same meter, and you'll get a remote wireless signal at that point.
In my case I plugged a remote unit in my garage and I now get wireless performance there that's about equal to what I get when I'm in the same room as the wireless router. I will warn you that these devices claim to be plug and play but my older router doesn't have a WPA button so I had to configure them.
Instructions were horrible and I had to do a lot of trial and error to get them working properly. I'm also not sure how stable they are, I've had to reset mine about once per week. But, I'm generally happy with them and they were the only option that solved my problem of getting wireless to my garage.
So, I'm currently using the 9 dBi antennas, a wireless repeater in my house and a power line extender to get the signal to my garage. If I were starting over again I'd just buy the power line extenders with 2 or 3 remote units. Unfortunately, it's the most expensive, and at least in my case, the most complex to set up, but it's easily the most effective way of extending your wireless signal that I've seen.