This item is primarily meant to be a handle to grip onto to help a person with limited mobility to get out of bed, not a rail to keep the person from rolling out of bed. We have it installed near the head of the bed- it might partially guard against accidentally rolling out, but it is not in the way of being able to swing one's legs over the side of the bed.
From the floor is adjustable, so it must be the top.
Check the height of the bottom of your mattress/ top of your box spring. For example, the top of the box spring on my grandmother's bed was at 14 inches. The device was actually intended to be used at a height of 17 inches or taller, so actually had to saw 3 inches off of the legs of the rail to be able to install it on that bed. If you have a bed with a higher box spring (or higher platform) you should be able to use the device without modification.
The adjsutable height is 13.5 - 16.5 inches.
Thank you for your recent inquiry with The Home Depot. The Drive Adjustable Height Home Bed Assist Handle is an Online Exclusive and can be shipped anywhere in the continuous United States. We appreciate your business and look forward to serving you in the future.