31 attaches to the proximal transverse edge 22 of the carrier 20 while the first and second arms 32 33 attach to opposite longitudinal edges 21 of the carrier 20 collectively the two arms 32 33 of each of the two elastic end straps 30 in tension removably and wrappingly engage the four corners of the mattress 10 and pull the transverse edges 22 of the carrier 20 against the top surface 11 of the mattress 10 and towards the transverse sides 14 of the mattress 10 thereby developing a tensile stress in the carrier 20 in the direction parallel to the longitudinal edges 21 of the carrier 20 in one embodiment the end straps 30 are elastic in another embodiment the end straps each comprise a length adjustable strap which allows the first and second arms 32 33 to be pulled towards the middle portion 31 in which case the end straps are not necessarily elastic in one embodiment as shown in fig5 the end strap 30 has a multi layer construction with an inner layer 34 made of a pliable elastic material such as neoprene laminated and bonded to two outer layers 35 made of a pliable fabric such as polyester the outer layers 35 may be constructed.