There are a few versions of it. The older ones like the Double Ring, the Single Ring, the Bulldog are basically the same razor with different handles. Later on Gillette decided to make them with thicker top caps and base plates.
For whatever reason, I find the ''older'' style of the thin top cap and base plate combo a bit better compared to the ''newer'' ones with the thick top cap and base plate.
The regular Single Ring as well as the 1921-1928 Old Types aren't that expensive or hard to find and are worth going after.
I have a later three piece thin cap and thin baseplate from my Grandfather. At one point, I also bought a thick cap and thick baseplate version. I found they do shave a bit differently, but not enough so to where if you had one that it would be worth buying another of the other thickness.
Now, the New Improved does shave differently enough to where it's worthwhile to have one of those as well. And, this also applies to the New Short Comb and New Long Comb. And, I prefer Grandpa's Thin Cap and Baseplate Old Type the best of all of them.
But, I think all should be experienced by each of us to determine which each like the best.
I have many of these razors models 102 and 102a. Everyone shaves differently. Some are softer, others are sharper and more aggressive. It does not depend on whether 102 or 102a. Buying is a lottery. You never know which one you will get. But I am a fan of this razor, this is my favorite razor from Gillette.
Absolutely amazing shave this morning with the Big Fellow. Twisted back for the face and efficiency was off the charts just like with the Bulldog. Snugged down for the neck. Still very efficient. I LOVE the longer handle and the weight. It's perfect.
This is now the 4th variation of an old type I've tried and it's yet again ever so slightly different. The Big Fellow has a medium top cap, thick baseplate, and thick comb teeth. I thought this would feel more like the Brownie or Goodwill but was very similar in feel as the Bulldog. Smoother then the Goodwill and milder then the Brownie.
All efficient and I guess aggressive. Bulldog was probably the easiest on my neck and smoothest feeling. Big Fellow right there with it but it was like the angle was slightly different. I didn't feel the teeth as much either. The Goodwill slightly more aggressive or blade feeling but not terrible.
The Brownie had the most aggressive and blade feeling to it but the least efficient which is weird. I had to do more touch ups with the Brownie then the others and got a ton more feed back from my alum stick even in areas I didn't have to touch up.
The Bulldog and the Big Fellow are tied as my top picks here to shave with for smoothness, efficiency, and with the adjustable twist back super efficiency.
Another difference I just noticed is the width of the thick baseplate is slightly wider then the thinners ones. Can see that in the last couple pictures between the Bulldog/Goodwill and the Big Fellow/Brownie.