We recently improved free standing bilayers using a thiolipid layer on gold which also permits magnetic contrast reflectometry. One use for this system is to contribute to our longer term plans to make models of bacterial outer membranes in which a periplasm separates the outer and inner membranes. Recent beam time has enabled us to achieve two milestones, demonstration of high levels of asymmetry and the formation of the complete model with both LPS and outer membrane proteins. In this proposal we need to complete specific measurements to enable a high impact publication.1. we have shown that removing calcium increased the flip flop of LPS/PC across the membrane. This recreates for the first time in vitro an important effect seen in vivo. This needs repeating with and without membrane proteins. 2. we wish to demonstrate function by binding an antibiotic protein to the surface.