Mark's top link is as good as any.
Couple that with excellent service, and you can't beat it.
Example:
My first top link I bought from him broke ... it popped off the rod end when I lifted my box blade. I called him and he sent out a replacement at no cost AND a prepaid return slip for the broken cylinder. In other words, he sent out the replacement top link along with the return slip...not after he received the broken one. No hassles whatsoever!
I have used his DPOCV on several implements, where the valves were bad. They are top notch and about 1/4th the size and weight of Surplus Center's. I've bought at least 6 of them for various uses where I need to keep the cylinder in the position I choose. He sends all the hardware needed to install them, so it is an easy addition if you need that for your applications.
Point is, Mark does a great job as far as I'm concerned. I have no reason to look elsewhere.
Signed, satisfied customer.