I like to go small on space heaters and the ceramic cubes are that. One caution follows this.
Tip over switch/sensor and Thermal fuses are not mandated on them far as I know so you should not be able to buy one that does NOT have those features.
now the caution.
I've had one outlet overheat from 1500 watts. I replaced it (thankfully no damage) and I also made another change (Follows) I've seen a few that were burned up. and I mean DANGER type burned up from use of space heaters.. I do not trust the Uni-box type outlets at high current. the punch down type connection is just not enough for the job.
What I did to "Fix" it was install a pair of 15/20 amp outlets one in main room one in bedroom and a 2nd Kitchen circuit (GFCI 15 amp outlets but read on)
All 3 are fed with 12ga, not 14ga and bent around screws, not punch down. Each has a circuit breaker dedicated to just that outlet Or pair in the kitchen One is 20 amnp. the other two 15 (kitchen is 15) No smell of hot wire since.