When I first got the Mk.3 Jazz I thought the front seat floor brackets were missing plastic covers but , probably due to a cost cutting exercise , Honda have left them as a metal foot with an ugly bolt head.
No covers are available but Honda do spare bolt caps ( part no. 90650SJKL01 @ 97p ) , makes them look a little better.
The bolt heads are 14mm if you can source your own.
Mrs. pebbles Mk2 Honda has neat plastic covers.