an inner portion 66 the outer portion 64 engages the inner portion 14 of the shell 10 the outer portion 64 may be tapered to match the taper of the inner portion 14 of the shell 10 or the outer portion 64 may be cylindrical the sleeve 62 includes two ends 68 70 that create a recess 72 the two ends 68 70 extend inwardly via an extension portion 73 toward an apex 74 of the shell 10 the two ends 68 70 are uniform and encircle a hole 76 in the apex 74 the extension portion 73 can act as a spacer so the sleeve 62 may also work as a trial liner during surgery when the shell 10 is implanted a user may sometimes put a trial liner 100 in the shell 10 fig7 the shell 10 and trial liner 100 then engage the head 102 fig7 to check range of motion as illustrated by arrows in fig7 in the embodiment illustrated in fig5 the extension portion 73 allows the user to trial off of the sleeve 62 without the need for a separate trial liner the extension portion 73 has the same thickness as a liner so the range of motion of the head can be adequately tested this reduces inventory and makes the process simpler for the user fig6 shows another embodiment of a sleeve 82 the sleeve 82 includes an outer portion 84 and an inner portion 86 the outer portion 84 engages the inner portion 14 of the shell 10 the outer portion 84 may be tapered to match the taper of the inner.