Hello,
You'd need either a round end socket, or round end bracket.
For example Smith & Locke Rail End Socket White 19mm 2 Pack (979HH) or Smith & Locke Rail End Bracket White 19mm 2 Pack (223HH)
Also, if you would like additional support for the centre of the bracket you'd need Smith & Locke Rail Centre Bracket White 19mm (488HH).
Thank for using Q&A.
Answered by: DGIFF
Date published: 2020-11-09