[squeak (Andrew)]

i have a celestron powerseeker 127,with a claimed focal length of 1000 mm.the max distance that i can measure, from the primary mirror to my eye,is 500 mm. could someone please explain this (apparent) discrepancy ? also, the eyepieces that came with it are "k 20" and "sr 4" . what do the letters stand for? ( my 10" dob, f/l 1200 mm, does measure 1200 mm from primary mirror to eyeball) thanx.