A safety rail apparatus is provided, which comprises a post with a base configured to reversibly engage with a floor and providing support for at least 12 kN load, a rail holder configured to hold a rail in reversibly fixed engagement with the post and a plurality of components which are together operable to adjust the height of the post between a lower height of 900 mm-1.2 m and an upper height of 1.9 m-2.5 m. The plurality of compontents is further configured to adjust the height of the post to the lower height during one stage of a construction project and to the upper height during another stage of the construction project such that the upper height is at least 1.8 times higher than the lower height. The apparatus further comprises a mesh support configured to reversibly engage with the rail and support a mesh.