Northwest Short Line - 7418-4 - Wheel, Rail - Painted/Unlettered - 4-Pack

Specific Item Information: 4 Axles - typically enough for one car.

Prototype History: A train wheel or rail wheel is a type of wheel specially designed for use on rail tracks. A rolling component is typically pressed onto an axle and mounted directly on a rail car or locomotive or indirectly on a bogie (UK), also called a truck (North America). Wheels are cast or forged and are heat-treated to have a specific hardness.
Railroad car wheels are affixed to a straight axle, such that both wheels rotate in unison. This is called a wheelset.

Wheels and wheelsets are found in various diameter and axle length. This variety is also reflected in model trains.
The most common axle lengths for N scale model trains vary from 0.538 inch (MTL) to beyond 0.576 inch (Arnold-Rapido). See this blog article for more details on N scale wheelsets.

Road Name History: Some items are designed to have their owner add whatever company marking they choose, usually in the form of decals or dry-transfers. These items are painted in a generic prototypical fashion but with all company affiliation deliberately left off.