The 818-SL/DB Silicon (Si) Photodetector is supplied with a NIST traced calibration report that details individual detector responsivity measured with and without attenuator. Exclusive OD3 attenuator technology extends the calibrated optical dynamic range of our photodiode sensor heads by three decades. The serial numbers for the detector and the attenuator are matched to ensure NIST traceability. The 10 mm clear aperture with the cross hair will improve the detector alignment to the input optical beam more accurately and help avoid detector overfilling. This model includes a BNC/DB15 calibration module. The adapter contains the detector calibration data, model number, serial number and calibration date for seamless operation. Also available are a variety of accessories such as collimating lens assemblies, fiber optic adapters, and a bare fiber adapter, and a 1 inch optic holder. Note that Model 818-SL/CM is available offline only. Model 818-SL is no longer available.