McMaster 30305T542 Samson Caster with 4 1 2" x 4" Mounting Plate, Swivel with Total Lock and 4" Diameter Phenolic Wheel G4016822 4 Degrees F Specific Gravity 4 Degrees F Specific Gravity 1 Lined Bearings Surface Roughness 8 12 RMS Shaft Hole Spacing 150 mm Shaft Drilling Pre Drilled Shaft Material Grade 440 System of Measurement Metric Product Type Linear Shaft Shaft Hardness RC 60 Shaft Material Finish Polished Standards ISO Shaft Material Stainless Steel Shaft End to Hole 75 mm Roughness 8 12 uin RMS Number of Mounting Holes 1 Mounting Hole Type Tapped Shaft Type Pre Drilled Shaft Weight Per Meter 1 Oil Fabrication Stamped Material Zinc Plated Steel Mount Type Plate Mounting Fasteners Included No Center to Center Length (A) 3 5 8" Center to Center Length (B) 3" Center to Center Width (A) 3" Center to Center Width (B) 2 5 8" Length 4 1 2" Width 4" Type Ball Seal Type Open Construction Dual Raceway Swivel Lock Activation Foot Pedal Tread Style Flat Wheel Tread Material Phenolic Country of Origin United States DFARS Compliance Specialty Metals COTS Exempt Export Control Classification Number (ECCN) EAR99 REACH Compliance Not Compliant RoHS Compliance RoHS 3 (2015 863 EU) Compliant Schedule B Number 871690 They have nonmarking phenolic wheels that roll best on smooth surfaces