Rebutia marsoneri
(This plant comes in a 3.5 inch pot. You will receive a very similar plant to the one in the picture. It may or may not be blooming at the time of your purchase. The plant is shipped in its pot to prevent any damage to the roots).
Rebutia marsoneri
Description: Rebutia marsoneri is a small and very free flowering cactus species with bright yellow to bright orange blooms.
Flowers: Rebutia marsoneri develops a larger crop of flowers from the base of each head, resulting in a superb display in mid-season. It has bright golden yellow to orange or orange-red flowers.
Cultivation and propagation: Full sun to light shade. Water regularly in summer but do not over-water. Keep dry in winter. Hardy down to -4°C.
Some of the information in this description has been found at desert-tropicals.com, llifle.com and cactus-art.biz