ITEM NAME:10X Extruder Strong Printer Spring For Printer Heated Bed Ultimaker Makerbot M& Descriptions: The wire diameter: 1.2mm Inner diameter: 5mm Outside diameter 8mm Height: 20mm Material: stainless steel circle number: 9 Super elastic Note: Please allow 0-1mm differs due to manual measurement. Item color displayed in photos may be showing slightly different on your computer monitor since monitors are not calibrated same Package included:10PCS*Spring.Super elastic. Material: stainless steel.