What is "inside callipers"

Inside \In"side`\, a.

1. Being within; included or inclosed in anything; contained; interior; internal; as, the inside passengers of a stagecoach; inside decoration.

   Kissing with inside lip.
   --Shak.

2. Adapted to the interior.

   Inside callipers (Mech.), callipers for measuring the diameters of holes, etc.

   Inside finish (Arch.), a general term for the final work in any building necessary for its completion, but other than unusual decoration; thus, in joiner work, the doors and windows, inside shutters, door and window trimmings, paneled jams, baseboards, and sometimes flooring and stairs; in plaster work, the finishing coat, the cornices, centerpieces, etc.,; in painting, all simple painting of woodwork and plastering.

   Inside track, the inner part of a race course; hence, colloquially, advantage of place, facilities, contacts, etc., in competition.