Jumbo pencils- Yes, but I don't like the grips part of those Faber-Castells out of personal preference. Quality wise- they're Faber-Castells, one of the two major companies of Germany's pencil industry...nothing wrong with them.

Prefer the Castell 9000 Jumbo (not cheap though), or, Staedtler's jumbo learner pencils. which usually are a little cheaper with no quality difference (made in Germany).

If you like Mitsubishi Uni, I'd probably also toss in any of their 'kakikata' AKA 'school' pencils - they are very well made and the B/2B grades are darker than European or American of the same grade. Other companies like Tombow,Showa, Kutsuwa, Sun-Star, etc make school pencils as well and I haven't found one I hate yet.

If you have a Daiso, anything from them as well. In particular, if 'dark' is your objective - these Kitaboshi pencils are very dark for their grade. Golden Sword and their house brand of 'kakikata' pencils also are good.