Single mode adapters are mostly either blue (UPC) or green (APC). They are colour coded so that installers can deduce the type of mating connector easily. SM adapters have stricter specs than MM adapters. It is due to the size of the fiber core. APC adapters have even stricter standards than UPC adapters. Our SM adapters are One Piece models, i.e. the outer shell is cast from one part. It is therefore not possible for adapters to break in two, as in two-part models.
