Tri-Cam passive protection. Seems very effective for horizontal cracks. I bought it, but I was too scared to use it. I have two #3s. One is a bonus. Would anyone who can use it actively be interested? This product functions without problems, but please understand that it is a used item and use it at your own risk. If possible, I would like to have it delivered via Eco-Mercari's unattended delivery service. Thank you for looking.