I had a Mk1 Laguna Estate to which I fitted the genuine Renault dog guard - it was very, very good.
The guard was made of tube steel outer rim with cross wired meshing. Finished in grey powder-coat paint. (Even had a 2" approx diameter Renault badge in one corner!)
Fitting was simple - the two top stays fitted into the upper seat belt mount blanks (for the optional rear facing seat) while the bottom brackets fitted to the seatback retaining catch plates. A very solid fixture - I would like to think the Mk2 or onwards Lagunas have such a worthwhile and functional accessory.