ST to SC hybrid adapters are designed for mounting in panels with rectangular cut outs. This adapter features a bronze alignment sleeve which provides durability and resistance to cracking. Additionally, this adapter can be used with PC or UPC style fiber connectors. Contact us today for large project volume discounts. FC to SC hybrid adapters are designed for mounting in panels with square cut outs. This adapter features a bronze alignment sleeve which provides durability and resistance to cracking. Additionally, these adapters can be used with PC or UPC style fiber connectors. Contact us today for large project volume discounts.