Paternally sperm-supplied factor required for embryogenesis (PubMed:8565851, PubMed:20971008). Plays a role in preventing polyspermy possibly by promoting the formation of a continuous and cohesive eggshell chitin layer (PubMed:20971008). Localized to the perinuclear region of sperm. Expressed in mature sperm. Expressed during spermatogenesis. Worms fail to complete meiosis, form a weak eggshell, fail to orient properly the first mitotic spindle and fail to undergo cytokinesis.