An Australian firm unveiled an electronic shark repellant unit Wednesday that attaches to a swimmer’s ankle and emits an electronic field to ward-off sharks.

The SEACHANGE™ Shark Shield™ is a miniature version of cumbersome anti-shark pods used to protect triathletes in Sydney Harbour during the 2000 Olympics and worn by abalone divers.

The personal anti-shark unit weighs 450 grams (one lb) and has a battery life of two hours. A slightly larger unit for scuba divers weighs 590 grams (1.3 lb) with a battery life of four hours.