TBI Pro Dog Shock Training Collar with Remote Manual Focus Override in AF Mode Accepts 58mm Filters EF-S Mount for APS-C Format EOS Cameras One Aspherical Element Supports Movie Servo AF Feature Smooth and Quiet AF Ideal for Video Optical Image Stabilization Stepping Motor, Internal Focusing Syste 28.8-88mm Zoom Lens (35mm Equiv) Aperture Range: f/3.5-38