We tried a lot of different SMA-Male to N-Male adapters before deciding that none of them were good enough and started making our own instead. These adapters use high-quality RG142 cable that is durable and strong, and unlike most other adapters won't fall apart during installation.
This is a 50 Ohm impedance adapter (both N-type and SMA connectors are 50-ohm connectors).
The RG142 cable we use is double-shielded with silver-plated copper braid for maximum protection and performance. The 0.037 inch inner conductor is made of copper-clad steel with silver plating, and the inner dielectric is made from PTFE, while the jacket is a tan-colored fluorinated ethylene propylene (FEP).
The high quality materials allow for greater than 88 dB shielding, and this high quality adapter is rated for use at frequencies of up to 6GHz.