Inflate the collar via air valve(pinch & blow). Please put the zipper together when inflates. Inflate until it feels full, but not hard. Fasten everyday collar onto your pet and stick the strap that should be placed at the back of the neck then adjusted it for a perfect fit. Size information Size S: Neck diameter: 4-5cm Neck circumference:18-30cm Size M: Neck diameter: 7-8cm Neck circumference:25-36cm Size L: Neck diameter: 13cm Neck circumference: 38-50cm
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