Physical sensing accurate measurement. Mechanical induction element. Clear scales no radiation no batteries. Orange zone is the optimal temperature range for extraction. SUS 304 rapid temperature sensing and heat conduction. The 4mm probe is durable,safe temperature measurement. Oxidation resistance, Crrosion resistanceigh. Removable slingshot clamp, simple depth adjustment. Plugged into the hole of the lid. Clamped to the edge of the container.