Usually the parfocal length Infinity microscope is 45 mm 60 mm, some others are 75 mm.
This item can be used to match a variety of different parfocal lengths, can extend the parfocal length by 5mm 6mm 7mm 8mm 9mm 10mm 12mm 14mm 15mm 16mm 18mm 20mm 22mm 24mm 26mm 28mm 30mm.
Perfect microscope accessories, exquisite workmanship, can be widely used in microscope. With good durability and stability.
You can reach us anytime for any query and I'll available 24x7 to assist you, have a good day.