Reading the code1610-1″ is a 1610 bush with a 1″ bore. The bush size (1610) must match the pulley; the bore must match your shaft.
Bush sizeThe bush size is shown in brackets in the pulley code, such as SPZ 100 X 2 Groove (1610). The last two digits are the bush length in tenths of an inch, so a 1610 is 1″ long.
Metric or imperial?Measure the shaft. Imperial shafts take inch bores with an imperial keyway. Don’t mix them: the keyway won’t fit properly.