Sturmey Archer Pawl Spring
If you have lost the little tiny hair sized spring then this is what you are looking for!
This is the Sturmey Archer Pawl Spring also called an R Spring (try saying that quickly without laughing, especially if you have lost it!)
Used in the following Sturmey Archer hubs (and probably more):
Brompton Sturmey Archer BWR - Brompton Wide Ratio - 3/6 speed
Brompton Sturmey Archer BSR - Brompton Standard Ratio - 3 speed
Sturmey Archer AW 3 speed
Sturmey Archer S3C 3 speed / coaster brake
Sturmey Archer S5 5 speed
Sturmey Archer SAB3 3 speed / hub brake
Sturmey Archer X-RD5 5 speed
Sturmey Archer X-RF5 5 speed
Sturmey Archer X-RK5 5 speed
Sturmey Archer AB5 5 speed
Sturmey Archer S5 5 speed
Sturmey Archer X-RC5 (W) 5 speed
Sturmey Archer S-RC5 (W) 5 speed
Sturmey Archer SRF5 (W) 5 speed
Sturmey Archer SSC (W) 5 speed
Sturmey Archer X-RF5 (W) 5 speed
Sturmey Archer XL-RD5 (W) 5 speed
Sturmey Archer X-RD5 (W) 5 speed
Sturmey Archer S-RF3 3 speed
Sturmey Archer ref: HSA120
Made in Taiwan