Describe Slim the jerkline skinner? What sets him apart from other men?

The jerkline skinner at the ranch, Slim is a seemingly ageless man who carries himself with great gravity. He gives Lennie one of his new litter of puppies to care for. Curley initially suspects that his wife is having an affair with Slim.

Slim’s a jerkline skinner. Hell of a nice fella. Slim don’t need to wear no high-heeled boots on a grain team.