Symmetric and transitive but not reflexive relation on the integers

Question

Can I get an example of a relation that is symmetric and transitive on the set $Z$

By Definition:

1. $R$, a relation in a set $X$, is reflexive if and only if $∀x∈X$, $xRx$.
2. $R$ is symmetric if and only if $∀x,y∈X, xRy⟹yRx$.
3. $R$ is transitive if and only if $∀x,y,z∈X, xRy∧yRz⟹xRz$.

I know you can make a symmetric and transitive function that is not reflexive in general, i'm having trouble finding one on the set of integers.

And can we say anything in general about such relations?