Marginal at best - Armasight Hands-Free Night Vision Monocular Kit for Spark / Sirius / Mini-NYX14

While it does of course "fit" the Armasight Spark I have it is tricky and time consuming to adjust. There are no instructions included although doubt they would help. The chin strap and "D" rings are quite flimsy ( the chin strap is actually more of a ribbon that pleats together and twists the ring rather than tightening the strap properly) I replaced the chin and the strap over the crown with a heavier Velcro strap which did help. Better to commit to using a helmet with appropriate hardware.