We have one, two, three of these thick filaments in this particular sarcommer. Now, let's begin by discussing what the composition of our thin filament is. The thin filament is composed of a type of globular spherical protein known as actin. And these individual actin monomers basically join together and combine to form a polymer, a long chain of actin. And two of these actin polymers basically intertwine with one another and form a helical structure that creates our thin filament. So the thin filament consists of two long polymers and these polymers consist of our actin molecule, the actin protein.