Both are Mamm plumosa. Jordi

Very nice! I grew this plant many years ago and it bloomed profusely. I pollinated the plants, harvested seed, and now, fifteen years later, sowed the seed and have tiny seedlings growing.

I think it should be "Mammillaria matudae". It depends more on the size of the root ball than the size of the plant, but it sounds as if it is time to repot it. The pot should not be too big, perhaps an inch wider than the root ball. A clay pot could be wider as it dries out quicker, I believe.

Aztcqn, you have beautiful plants. Love them. This one is great with the little ice crystals on the tubercles. Harry, yes, that fight against mealies... I had a lot in Holland in the seventies. Every year there would be a seller with cacti on Ascension day, the flower market in Leeuwarden. I had never seen a blooming cactus in my life. Bought a M. zeilmannia and a Rebutia minuscula. That was the beginning of may more. Fight against mealies and red spider mite, combined with a few international moves, stopped that. Like you, I am getting back into them a bit. No luck in Leeuwarden any more?