What is the preferred method to support a shower floor, eliminating all movement, when installing on a concrete basement floor? The previous shower unit had slight movement which resulted in leaking.

What material is it, and does it have full contact with the cement slab or is there a void under it?

Don't know yet. I am picking it up Tuesday. It is some type of plastic derivative, and I am assuming there will be a void based on the concerns he had with the previous tub.

It is polyethelene. It came with a styrofoam base which conforms to and supports the entire floor. I quess that answers my question. Thanks for offering to help.