Valcom V-2901A Enhanced Single Door Answering Device That Activates Door Locks<div style="text-align: left;"><strong>[Product Information]</strong><ul><li id="replacementPartsFitmentBullet" class="aok-hidden" data-doesntfitmessage="We're not sure this item fits your " data-fitsmessage="This fits your "><span class="a-list-item"><span id="replacementPartsFitmentBulletInner"><a href="#" class="a-link-normal hsx-rpp-fitment-focus">Enter your model number</a>to make sure this fits.</span></span></li><li><span class="a-list-item"> Door unlock contact closure (strike plate required) </span></li><li><span class="a-list-item"> Alarm functions </span></li><li><span class="a-list-item"> Transmit and receive volume controls </span></li><li><span class="a-list-item"> Background music input with volume control </span></li><li><span class="a-list-item"> Built-in ring generator with on/off switch </span></li></ul></div><img src="http://ecx.images-amazon.com/images/I/41Zzv0eV5PL.jpg" noproxy>