Patent ID: 7340929

Claim:
A lock apparatus able to be installed in a structure comprising: a) an outer sleeve having a plurality of outer rows extending transversely therethrough and radially therearound and a first bore extending though substantially a center thereof; b) an inner sleeve having a second bore extending through substantially a center thereof and releasably connected within said first bore, said inner sleeve having a plurality of inner rows extending therethrough wherein each respective inner row is aligned with a respective one of said plurality of outer rows, said inner and outer sleeves together forming a lock cylinder; c) a plurality of user selectable sleeve pin sets positioned within said plurality of outer and inner rows; d) a lock core for receiving a key therein releasably connected within said second bore having a plurality of core pin sets in a single row aligned with any one of said sleeve pin sets; e) an unlocking key for each of said sleeve pin sets; and t) a master key for removing said lock core from said lock cylinder ewe for rotating said outer sleeve with respect to said inner sleeve to align another row of sleeve pin sets with said core pin sets in said lock core whereby returning said lock core to said lock cylinder requires another unlocking key to open said lock apparatus.