In original OWL, the special loot level list (which mostly decide what gears you get in boss chests) will grant the weapon or armor of dedicated tier depending on your level and the zone's min/max level. While it creates a sense of progression, it lacks the randomness for me. Also in some of the patches, there are some of the high level gears put in lower tier sublist, which you will not get from chests once you pass through that level. But I do not want to simply add the probability to get all tier's gear by chance, because it is no fun to get an iron sword in vampire boss chest at high level.

So to counter the above issue, I implemented an additional layer to the special loot level list in the Randomized Special Loot Addon. This new mechanic now divide the loot into 3 tiers: Low, Mid and High. Each tier contains a range of gears depending on their material, your loots will draw from each tiers' pool according to different level marks (your level and the zone's min/max level).
Low Tier: level 1-10, contains iron to steel gears.
Mid Tier: level 10-30, contains steel, dwarven, elven, orcish gears. (With progression listed in description page.)
High Tier: level 30 and above, contains glass, ebony, daedric gears. (With progression listed in description page. Also for armor list there are also steelplate and scaled in the mix. )
*Solstheim has regional special gears like chitin, nordic and stalhrim.

All in all, consider this addon an update of OWL. Highly recommended! 

Remember to put the plugin below all the patches in load order, even below your bashed patch.