You can not use just rails on king beds as the box springs are a split box , so you need a bed frame with Headboard and foot board attachment.
https://www.ambfurniture.com/Hollywood-Bedframe-1207HF-Cal-king-size-non-adjustable-style-bed-frame-with-glides-with-headboard--footboard-attachment.html
https://www.ambfurniture.com/Hollywood-Bedframe-1206HF-Queen--eastern-king-size-non-adjustable-style-bed-frame-with-glides-with-headboard--footboard-attachment.html
Answered by Anthony Bianco on Jul 12, 2019