Furthermore the fact that you'll get more rewards for opening Medium Casket than you would with a simpler one (so you can expect things like shield h3, shield h2 or helm H3). Alongside The Ranger Boots with a special drop list RS Gold, it is possible to find Spiked Manacles that cost over 1 million. Other benefits aren't nearly as valuable like these two items.
While it does have a similar unique drop table in value to Medium Casket - from hard difficulty, you also are able to roll from the mega-rare table. You can get a wide range of items that are extremely costly such as 3rd Age Equipment and Gilded Parts that have a value of hundreds or even tens of billions (like 3rd Age Platebody). Additionally, items on a unique drop table are valuable because they cost over 1 million gold. In addition, you get more rolls at rewards with a Clue than you do with a Medium One So, generally you should get more drops.
Just like with the previous box, this casket gives you the chance to roll for unique and mega-rare items with worth tens or thousands or even millions. The difference between this casket as opposed to the previous one is that it has higher chances of receiving Gilded drops and a less of a chance to find Third Age items.
There are also less frequent drops that have a low value overall and more which have a value of 1-10 million, such as Fury Ornament Kit Old School RuneScape Gold, Saradomin Ornament Kit, Ranger Chaps, Ranger Gloves, Sagacious Spectacles Fremennik Kilt Black Tuxedo Jacket, White Tuxedo Jacket or Dark Trousers.