Infelizmente, a descrição deste produto ainda não está em Portuguê portanto, você encontrará uma descrição em Inglês do produto aqui.
With the T2 locking ring you can finely adjust the distance between two T2 threads. The only requirement is that the male T2 thread needs to be long enough. The locking ring is only 1mm thin, much thinner than most other locking rings.
How to use the locking ring: Screw the T2 locking ring onto the male T2 thread of an adaptor. Then screw on the next adaptor (or camera), but only as far as necessary in order to reach the desired distance. Finally just lock it by screwing the locking ring against it.