Tuttle Beijing 3 or Tuttle beijing 4

TB3 and TB4 are really, really different.

TB3 is hard, tacky. Similar to Haifu Whale 2 (some say it's a cheap alternative to Whale 3 actually, but I've never tried Whale 3 myself). Typical hard, tacky Chinese rubber. A good example of the genre. Nothing like Shark 2.

TB4 is super soft, not tacky, medium-fast, bouncy, grippy. Wears out quite quickly (but it's cheap enough to compensate), low throw, quite insensitive to spin, loud cracking noise. It was a great BH rubber for me, and I used it for a while on that wing. Great for blocking, hitting, surprisingly good for the odd chop. Shark 2 (on a soft sponge) is along these lines. Shark has a grippier topsheet, bit faster, more durable. Shark is the more grown-up rubber, but I love both TB4 and Shark 2.