裡手

expert / left-hand side (of a machine) / left-hand side (driver's side) of a vehicle

lining / interior / inside / internal / also written 裏|里[li3]

hand / (formal) to hold / person engaged in certain types of work / person skilled in certain types of work / personal(ly) / convenient / classifier for skill / CL:雙|双[shuang1],隻|只[zhi1]

connoisseur / expert