Teenager Repellent
Every teacher will want one of these. The SST reports on a device which emits an annoying high frequency sound which few people over 20 can hear. So it can disperse a group of teenagers and not affect adults.
Every teacher will want one of these. The SST reports on a device which emits an annoying high frequency sound which few people over 20 can hear. So it can disperse a group of teenagers and not affect adults.