As part of a refit for a 1978 Sea ray boat, I purchased 2 of these to hold the batteries instead of using battery boxes. The new location I had chosen for the batteries did not allow the extra height needed to drop a battery into a box so these were a good option. There is plastic tabs or flange to secure the tray and it needs to be fastened down near the center so they do not flex with you secure the battery posts. Once installed, they require no tools to be able to install and remove the batteries, while securing the batteries. This is ideal in a marine application as tools are not always available when you have a battery issue. I had two different brand group size 24 batteries and both fit properly. Now the batteries are visible for inspection and secured properly. The only advantage of a battery box is the terminals are not exposed, but that can be resolved by using cables with covers for the positive terminals. Will use on the next boat I am refitting.