Sonia G Lotus Builder is a brush.
Lotus Builder is a medium, shader brush and is supposed to be similar to Builder Three in the brand's permanent range but has undyed bristles. It features saikoho bristles, and it has a hair length of 10mm and total length of 150m.
I actually felt like this was a bit more compact and not as thick/dense as the Builder Three. The edge became fluffier than the Builder Three after a couple of washes, so it diffused products a touch more when they were sheerer. The shape is excellent for applying and packing on product to the lid or using the edge against the lash line to apply or blend out products. I use the Builder Three regularly (I have several of them), and I'll definitely add this to my rotation.