Check the listing for details. KBLF-23D (4739B) KB Electronics AC Motor Speed Control. Condition: Used. Listed at 239.00 USD. This KB Electronics AC Motor Speed Control, also known as KBLF-23D (4739B), is a reliable and efficient choice for controlling the speed of your AC-powered motors. It is ideal for use in various industrial automation and motion control applications, including drives and starters. With its speed control and power source options, this device is suitable for a wide range of usage scenarios. The brand name of this product, Speed Control, is indicative of its purpose and functionality. This speed control operates quietly and efficiently, delivering a powerful performance without any unnecessary noise or vibration. Whether you're running a business or working on a personal project, this AC Motor Speed Control is a versatile and reliable choice for all of your industrial automation and motion control needs.