High, Low Switches for ringer sound. To increase the volume of telephone ring in noisy places. To help the hearing-impaired to recognize ring coming. No Battery Required. No Power Cord Required. No Special Jacks Needed. Easy To Install. This Amplified Phone Ring Signaler is a small portable device that notifies a user of an incoming phone call with a ring up to 95 decibels. Never Miss A Call. Brand No Brand SKU 100234239_NP-1020487298