MultiFiber Pro sources are wavelength specific.
The MFMULTIMODE SOURCE is an 850 nm source.
The two single mode sources available are MF1310 SOURCE and MF1550 SOURCE.
Users testing MPO single mode links with MultiFiber Pro single mode sources have contacted TAC to ask which wavelength should be tested. More importantly, what does your contract with your customer specify? That answer should determine which wavelengths you test.
Ideally you would test single mode links at both 1310 and 1550 nm wavelengths. Generally speaking, the 1310 nm wavelength is more sensitive to alignment problems (i.e. loss events), and the 1550 nm wavelength is more sensitive to issues caused by bends and cracks in the fiber link under test. Comparing the 1310 nm wavelength loss with the 1550 nm wavelength loss can indicate a bend or crack is present if there is more loss at the 1550 nm wavelength than the 1310 nm wavelength.
An alternative testing solution is to use CertiFiber Pro with a 3 jumper reference.