Core Flyte (way better than any other sliders)
Single pulley system (can be stationary like TRX or free spinning)
tubing w/ changing attachment hooks (little more expensive, but infinite possiblities for use)
PUsh up handles (can be used solo or with all of the above)
Fit/Swiss ball (can be used solo or with all of the above)
And I would have to include a hard roller.
And don’t forget the client’s own body(ies).