welcome to the one of the epiphanies of learning spanish...
esta/este/esto = this (fem/masc/unknown)
estas/estos = these (fem/masc)
esa/ese/eso = that (fem/masc/unknown)
esas/esos = those (fem/masc)
There is no neuter form in plurals because, in Spanish, if you can count them, you know what they are, and thus, you know their gender.