The following fill levels are considered normal for the corresponding age group (in accordance with leading auction houses and rarity dealers).
10 years and older VTS/IN (sometimes also referred to as BON, Base of Neck)
15 years and older VTS
20 years and older TS
30 years and older HS (sometimes also referred to as Upper Shoulder or High Mid Shoulder; “between MS and TS”)
40 years and older MS