sizer

Short definition from Wiktionary

Noun

1. 1
   An instrument or contrivance to size articles, or to determine their size by a standard, or to separate and distribute them according to size.
2. 2
   An instrument or tool for bringing anything to an exact size.
3. 3
   Alternative form of sizar (“undergraduate who received an allowance”).

Proper noun

1. 1
   A surname.