There are four different capacity, 30,40,50 and 60 ml for the square airless bottles.
round-shaped / square-shaped
for skin care products, such as serum, lotion, cream, foundation and gel
30ml HDPE 50ml PETG
-- 100% PCR (the hand feeling is hard) -- 50% PCR + 50% LDPE (the hand feeling is softer)
--30ml/40ml/50ml capacity available
If your products are focused on natural ingredients, and you prefer the containers to be transparent for people could easily seeing through.