The Bolero line is a 10L kit that has been re-hyrdrated for you. In other words, RJS has added the water for you. The total volume is 23L, but these kits are just above the Grand Cru line. Here is a comparison of RJS to WE. Nothing in RJS compares to MM, as they have a unique product.
RJS to WE:
Cellar Master = Vintners Reserve (usually found in Grocery stores)
Ancient Vines = Vintner Reserve
Orchard Breezin = Island Mist
Vino del Vida = World Vinyard
Grand Cru = World Vinyard
Bolero = Nothing in WE
Cellar Classic = Selection Original
Cru Select = Selection International
Cellar Classic Winery Series = Selection Crushendo (Grape pack kits)
En Primeur = Selection Estate
Important to note though, is that some selection in Cru Select and now all the reds in the En Primeur series come with dried grape skins, which is about 10lbs of pre-dried weight of grapes, so in essence, they are skins packs too.
They've also just released their "Premier Cru" series, which might compare to MM products, but very few people have seen these products yet.
I do a lot of RJS kits as I live about 10 minutes from their head office. Of course I also live about 40 minutes from WE head office too. Cellar Craft is about 45 minutes away, and sadly Mosti Mondiale is on the other side of the country in Quebec.