75mm aperture, 500mm focal length. Excellent condition -- optics are untouched. Check out todd gross or ed ting's review: this is a small and lightweight 3-element refractor (SD doublet objective + field flattener) with very sharp optics. Includes tube ring, but no finder scope or diagonal (I'll throw in an Orion 1.25" mirror diagonal for $50 if you'd like). Focuser is 2.37"; comes with Pentax adapters for 58mm or 36mm threads and 1.5" tube; also includes APM adapter for 2" tube and custom made (aluminum) adapter for 1.25" tube. Let me know if you have any questions.