This Caster Series is designed specifically to withstand the excessive abuse and harsh environments that Nursery and Greenhouse carts experience from being pushed up and down delivery ramps, ran into curbs and other obsticles, being rolled over rough, dirty terrains and being left outdoors in the elements and sun. The wheel is UV resistant soft rubber on a hard rubber core, equiped with two sealed precision ball bearings with special integrated bushing / thread guards; made to maximize the bearings performance and keep out debris. The soft rubber tread is very durable and abrasion resistant, offering a smooth, quiet, cushioned ride with the ability to roll over uneven ground, broken or rough surfaces, gravel, dirt and small debris, that may be on the rolling surface (ie: asphault, cement, trailer floor, etc). The caster yoke is made from 1/4? thick cold rolled steal and has double ball raceways with upper and lower seals all held together by an ultra-strong 5/8? nut & bolt kingpin. Caster yoke has a zinc plated fi nish that is attractive and off ers resistance to rust. This caster was designed, formed and welded for optimal mobility, durability and long service life.