L ring
{{For|a lattice-ordered ring in mathematics|Partially ordered ring}}
The L-ring of the bacterial flagellum is the ring in the lipid outer cell membrane through which the axial filament (rod, hook, and flagellum) passes.{{cite journal|title=L-, P-, and M-ring proteins of the flagellar basal body of Salmonella typhimurium: gene sequences and deduced protein sequences. |vauthors=Jones CJ, Homma M, Macnab RM |journal=J Bacteriol |date=July 1989 |volume=171 |issue=7 |pages=3890–3900 |pmc=210140 |doi=10.1128/jb.171.7.3890-3900.1989 |pmid=2544561}} that l ring stands for lipopolysaccharide.