3656. The Videx 3656 is a surface mounted 3600 series 3.5 inch TFT LCD colour monitor with hands free speech facility and handset, designed to suit VK4K, VK8K & VR4KV Video Kits. The 3656 can be operated in simplex, half-duplex and (with the handset) full duplex mode. This product has dimensions of 161mm x 218mm x 62mm. Call tone volume, number of rings and brightness contras & hue are all adjustable.. Can be operated in simplex, half-duplex or (with handset) full duplex mode. Timed privacy with LED. Adjustable call tone volume. Local call bell input