Nauticam M10 Plug for Extension Rings 21270, 37301, 37303

90147 - Compatible with all 37301.  Compatible with 37303 before SN A336014.

90147 - Compatible with 21270 before SN A227954. 

90147B - Compatible with 37303 from SN A336014 and after.  

90147B - Compatible with 21270 from SN A227954 and after. 

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