ANDREA "Sanctus" rosin uses a unique formula that is the first in the world to combine two separate parts in a single cake of rosin. The main base of the formula is hydrogenated to have excellent oxidation resistance, which ensures the consistent quality performance experience throughout its long-lasting usage of the rosin. The center part is a newly enhanced formula based on ANDREA's "SOLO," and it is physically softer and thicker. The outer part is formulated to have harder and drier characteristics to give balance in sound and to protect the soft center formula of the rosin. The donut shaped outer rosin is made first, and then the center formula is poured into the hole of the outer rosin. It is still all hand poured which makes the process even more challenging.