The Keysight N1294A holds several optional accessories for B2900A series and you can choose any of them as necessary. The N1294A-001 and N1294A-002 are banana-triax adapters for low current measurement less than 1 nA. The N1294A-011 and N1294A-012 are interlock cable dedicated to 16442A/B test fixture. The N1294A-020, N1294A-021 and N1294A-022 are low noise filters dedicated to B2961A/62A. The N1294A-031 is a GPIO-BNC trigger adapter conveniently used for synchronization with other instruments. The N1294A-032 is a digital I/O trigger cable which is using with EasyEXPERT group+ software for multiple B2900A SMUs.