Speedo Unisex Adult’s Centre Snorkel, Blue/Tangerine, One Size $38.98 + Delivery ($0 with Prime/ $59 Spend) @ Amazon AU

Ideal for practising the facedown head position needed for butterfly and freestyle
SpeedFIT head strap for quick and easy adjustment
Vibrant multicoloured pattern to stand out from the crowd
Suitable for use with a mask or goggle