Micnova MQ-TMR01 Tripod Mount Ring for the Canon EF 70-200mm f/4L USM, EF 300mm f/4L USM & EF 400mm f/5.6L USM - (White) Professional Grade Improves Tripod-Mounted Lens Balance Simple to Install and to Remove Rotates for Horizontal/Vertical Shooting Thumbscrew Tightens and Loosens Ring