Flat eyelash extension is cross section is flat (common eyelash eyelash of round cross section), more easily for eyelash grafting, and not easy to fall off. This eyelash type is not round, but flattened to look wider, but the weight is only 60% of the normal eyelash extension. So it's more comfortable to wear. Beside, the attache space is larger then the normal round eyelashes, this increase the space for the glue and the eyelashes. So it can last longer. 
The split tips at the top looks more fluffy and voluminous perfect for stacking to create lots of volume.

But did you know that flat eyelash extension is divided into 3 different materials：Import materials, Chinese materials, faux mink materials.
1.Import materials features
Hair is super black, thick and hard,split tips short, hair is tall and strong
The same thickness looks thicker.
2.Domestic materials features
The hair is naturally black, soft and thin, with split tips long and wide and the grafting is natural.

3.Faux mink materials features
The hair is a bit dark, super soft, with split tips long and wide and the grafting is natural.

The same thickness looks thinner.