1746-N2 is a SLC 500 series module slot filler launched by Allen-Bradley (Rockwell Automation). The relevant information is as follows

Function and application: It is used to fill the unused I/O slots in the SLC 500 case, which can prevent dust, debris and other contaminants from entering the case, protect the backplane from damage, and help maintain the reliability and service life of the system.
Technical parameters
Working voltage: 10-30 volts of direct current.
Backplane current (5 volts DC) : 50 milliamperes.
Dimensions: 12.7×7.62×20.32 cm (5×3×8 inches).
Weight: Approximately 0.045 kilograms.
Operating temperature: -25°C to 60°C (-13°F to 140°F).
Non-operating temperature: -40°C to 85°C (-40°F to 185°F).
Relative humidity: 5% to 95% (non-condensing).

Safety standards: Complies with EN 61131-2 safety requirements for programmable controllers and the 73/23/EEC low voltage Directive. It has also passed Gost_r certification as well as Marine AB S, BVS, GL, KRS, LR and other certifications. It is suitable for Class I Zone 2, Groups A, B, C, D and non-hazardous environments.
Installation precautions: When installing or disassembling this module, the system power supply must be disconnected to avoid damaging the equipment.