What everyone is talking about? The real Russian Volume. And these are not cluster lashes that can be bought in a shop. Truth is that Russian Volume or 3D lashes are similar to traditional Classic lashes but instead much finer. Let me show you in a photo what I mean.

Classic eyelash extensions are natural – looking, synthetic Mink eyelashes applied one by one to each individual natural lash. This technique builds volume and length yet creating a natural look.
Russian Volume/3D – 4D eyelash extensions is an advanced technique to create volume. It involves the application of multiple (3 to 6) fine eyelash extensions to each natural lash. An eyelash extensions artist is collecting 3 or more individual lashes with their tweezers and making a fan. This is very time consuming and skilled technique that is why it costs a lot more than the Classic lashing. Russian Volume creates a way more dramatic look.
Note! 1 Classic synthetic eyelash = 2 Russian Volume synthetic eyelashes
If you want to achieve really dramatic look go for Russian Volume. But if you prefer more natural look I would suggest a combination of these two techniques. It looks amazing and lashes will last longer as well.