Brompton chain tensioner nut for 3 speed STURMEY ARCHER (steel shell)

Short Brompton chain tensioner nut

Technical notes:

This is the shorter 16.9mm nut used on old steel shell (2004 and before) hubs - using the SA I gear indicator chain

Current hubs (BSR and BWR) use a 19.5mm nut and use the SA II gear indicator chain

Chain tensioner / gear indicator nut:

(This is the nut with a hole in the side)
Earlier hubs 2004 and before (normally with steel shell) use this nut.
The difference between this and the later alloy shell nut may be small - but it is essential to use the right one. 

Brompton Q part code: QCTN3-SA[1]
Brompton old (pre-2013) Q part code: QCTN3-SA-01
Brompton part number: 9010103