I wouldn't waist your money, you're basically spending $30 on one hole saw as the only one you'll ever use is the 1 5/8" (42mm). I've drilled many, many holes the smallest one Ive ever used is 42mm and that was rare, 45mm is the standard for most 3/4" and some 1" bulkheads.
Rather buy exactly what you need from
TKH Diamond Tools
Best deal I've ever found, and I can vouch for them, they work well.