GoPro HERO3+ 0.16x High Grade Fish-Eye Lens (180° Diagonal Angle of View) + Gopro Adapter (37mm) - Walmart.com
GoPro on X: "Photo of the Day: Fish-eye flare with #GoProAthlete @TimJumphreys + a camera hack on #GoProHERO10 Black 🏂👇 #ProTip: To achieve this stylized look, add the Max Lens Mod accessory
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Fisheye Camera Lens 1.21mm 220 Degree 16 Megapixel 1/2.3" M12 Mount for GoPro Hero 4 3 Xiaomi Yi 4K SJCAM 360VR shooting - AliExpress