What is csfp transceiver?

2-Channel 1000BASE-BX-D BiDi CSFP 1490nm-TX/1310nm-RX 10km DOM LC SMF – OpticsWave

Huawei CSFP-GE-FE-BIDI2 BiDi SFP 1000BASE-BX-D TX1490nm/RX1310nm 20km Transceiver - QSFPTEK

1.25G-cSFP-21-AD: Compact-Size cSFP module supporting 2 x 1.25G

CSFP-GE-SM-10xxD CFP-SFP/SFP+/X2/光模块/光纤交换机/SFP BIDI

CSFP-1G-2BX-D-I-C MSA Compliant Compatible Transceiver - Prolabs

What is the difference between dB and dBm ?

LTM3401 CSFP Optical Transceiver - BiDi/CSFP - Hisense Broadband

CSFP at competitive pricing & highly compatible

Customized CSFP 1250Mbs 1310 1550nm LR 20km Manufacturers, Suppliers - China Factory Direct Price - HTF

Source Photonics FTM-33X1C-X10G