A spacer apparatus for maximizing a user's range of motion on a weightlifting exercise machine. The spacer apparatus includes a first interlocking part having a semi-circular body extending between top and bottom portions, and a lock portion extending between first and second ends of the semi-circular body. The first and second ends are spaced and a keyway is between the first and second ends. The spacer apparatus includes a second interlocking part having a body extending, at least partially, between first and second ends, and entirely between top and bottom portions. The body of the second interlocking part has a semi-circular portion with a key portion extending therefrom. In the interlocked configuration, the key portion extends between the keyway such that an outer perimeter of the first interlocking part and an outer perimeter of the second interlocking part are aligned.