20 pack of Polyethylen Round, Tapered, and Unthreaded Cap Plugs ( Metric )

12.4mm full specifics:

ID:   tapers from 14.00mm down to 12.40mm,

OD:   tapers from 15.40mm down to 13.90mm,

Height (internal clearance): 12mm

13mm full specifics:

ID:   tapers from 14.70mm down to 13.00mm,

OD:   tapers from 15.70mm down to 14.20mm,

Height (internal clearance): 12.88mm

14mm full specifics:

ID:   tapers from 15.50mm down to 14.00mm,

OD:   tapers from 16.80mm down to 14.90mm,

Height (internal clearance): 12.88mm