The Siemens 7ME3960-0DM20 is a pipe damping film used with D1 and D3 transducers on the SITRANS FS220 ultrasonic flowmeter. It carries the legacy part number CC129-1A-2, so if you're replacing that older reference, this is the direct drop-in. This is a consumable accessory — the damping film sits between the transducer and the pipe wall to improve acoustic coupling and reduce signal noise. You'll need it when reinstalling transducers after maintenance or on a new pipe spool.
It ships as a single piece, one unit per order. Group code R3P3, product group 4727 — those are Siemens internal classifications that won't affect your BOM line, but they confirm this is the correct accessory family for the FS220 meter.
Compliance note
One thing to flag for your compliance docs: this product is not RoHS-compliant. If your project requires RoHS exemption declarations or full material disclosure, you'll need to account for that. REACH Article 33 candidate-list information is available from Siemens upon request. Export control is straightforward — AL: N, ECCN: EAR99I, so no special licensing for most destinations.