1). We supply fiber optic types include: SC fiber optic connector, FC fiber optic connector, ST fiber optic connector, LC fiber optic connector, MU fiber optic connector, SC/APC fiber optic connector, FC/APC fiber optic connector, etc

2). There are Single mode fiber optic connector and Multimode fiber optic connector,
Single mode fiber optic connectors can be with PC, or UPC or APC Polish,
Multimode fiber optic connectors only with PC or UPC Polish.
PC or UPC or APC refer to how we Polish the ferrule of the fiber optic connectors.

3). Judging from the out looking, Multimode connectors are usually with black boot or beige color, Single mode PC and UPC ones are usually with blue or black color, Single mode APC is with green color.

4). Insertion loss is important technical data of the fiber optic connectors. The smaller the better. APC insertion loss is smaller than UPC, UPC is smaller than PC.