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SmallRig 4" Suction Cup Camera Mount Kit$79.99
It consists of a 4-inch suction cup, a magic arm, and a dust cover. The suction cup made of NBR can be used at temperatures ranging from -20 °C to 60 °C and does not easily deform. It can support up to 3 kg of weight.
The mount features 1/4"-20 threaded holes, 3/8"-16 threaded holes, and ARRI 3/8"-16 mounting holes. It is manually pumped and locked, and has a warning indicator.