OPTICAL DESIGN; CLEAR APERTURE 80MM (3.15"); FOCAL LENGTH, FOCAL RATIO 400MM F/5; MAXIMUM PRACTICAL VISUAL POWER: 275X; OPTICAL TUBE DIM: DIA X LENGTH; 3.6" DIA X 14.5"; INCLUDES 2 PREMIUM 4-ELEMENT 1.25" SUPER PLOSSL EYEPIECES (SP 9.7MM, SP 26MM) FOR LONG EYE-RELIEF & WIDE VISUAL FIELD; BUILT-IN BARLOW LENS FLIPS INTO POSITION WHEN NEEDED FOR LUNAR & PLANETARY SURFACE FEATURES; INTERNAL TIME CHIP KEEPS PRECISE FACTORY CALIBRATED TIME & DATE; BUBBLE LEVEL/COMPASS TO MAKE INITIALIZATION FASTER; TELESCOPE MOUNTING FORK TYPE; DOUBLE TINE; RA & DEC MOTOR DRIVE SYSTEMS; 12V DC SERVO MOTORS WITH ENCODERS; SLOW-MOTION CONTROLS ELECTRIC, 9-SPEED BOTH AXES; AUTOSTAR™ SUITE ASTRONOMER SOFTWARE ON DVD FOR PC, WITH INSTRUCTIONAL DVD; INCLUDES AUTOSTAR™ CONTROLLER #494; INCLUDES PLANETARIUM SOFTWARE & INSTRUCTIONAL DVD