Plastic and Steel Gravity Rollers. Originally developed for food and drink industries our high-quality gravity rollers are now in use across a wide range of industry sectors where light to medium loading is required. Our gravity rollers are available in either polished stainless steel, food quality Polypropylene or food quality blue PVC plastic. All nveyor gravity rollers are fitted with stainless steel shafts, springs (where required) and stainless steel/PVC plastic gravity roller bearings.