car stereo review Orion Shorty 1 25 Barlow Lens
Doubles your lens collection. My son has a 90mm mak-cass. He has two lenses that yield 50X and 75X. The barlow doubles them to 50X, 75X, 100X, 150X. This is about as large as a 90mm can go.
I use this barlow on my Dobsonian. I like having more magnification without reducing the exit hole on my eyepiece. Some eyepieces are not as good around the edges. A barlow gives a larger clear spot while increasing magnification. This is win/win. I often use the barlow, even if I have a lens that will yield the same magnification.
A barlow will give good magnification on items that can be magnified, such as the moon and planets. When looking at deep sky objects, I often like wider fields and lower magnification.
This particular barlow offers great bang for the buck.