There are multiple generations of these VSR Packings. They all work fine.
Delta is Accuracy and Monster is Range. Units are new and of the older Legacy design and manufacture - Circa 2013.
In the Transformer Series
Autobot is Range Type, Deceptacon is Accuracy Type - Circa 2015
In the Hero Series
Wonder is Range Type, Super is Accuracy Type - Circa 2017
Durometer is 50 Soft - 80 Hard
MR is Range Type - Circa 2020
Durometer is 50 Soft - 70 Medium
2021 Deceptacon/Autobot is Circa late 2020
Material is Silicone instead of rubber for chemical and abrasion resistance
2021 MR Hop is early circa 2022.
Durometer of 60 Soft - 80 Medium/Hard
They "all" work just fine and are often better than stock. Even better than Stock TM.
Works in any VSR type system from KJW, TM, WE (with barrel swap for best results) and other compatible Hop-up systems.
Shipping and Handling of $3.90 for first unit and .88 extra for each additional unit.