of the cement plug 28 as shown the wiper plug 54 includes a body 56 and an elastomeric sleeve 58 about the body having lips or wings thereabout flexibly engagable with the inner diameter of the casing string 10 to permit the wiper plug 54 to be pumped downwardly onto the cement plug 28 as compared with the body of the cement plug 30 the body of wiper plug 56 is imperforate and thus does not permit flow through it the upper end of the body 30 of the cement plug is attachable to a third anti rotational locking member 59 the lower end of the body 56 of the wiper plug is attachable to a fourth anti rotational locking member 60 the anti rotational locking members 59 60 of the wiper plug and the upper cement plug are similar and in the preferred embodiment are identical to the first anti rotational locking member 40 of the lower cement plug the form of which is demonstrated in fig5 therefore each anti rotational locking member 59 60 is composed of a cylinder 61 62 having one or more inclined plane j slots 63 64 about its circumference the inclined plane j slots 64 of the wiper are disposed so as to have the ability to make up with the inclined plane j slots 63 on the cement plug when a vertical force such as the weight of the wiper plug and a pumping force is applied to the wiper plug 54 to push it towards the cement plug 28 the vertical force causes right handed rotation between the plugs 28 54 so that they make up thus with the.