twin axle mover-Whats best Value please

When we had very recently a motor mover fitted to our c/van,one thing that was mentioned ,if the c/van is in storage and not used frequently,the electric apply ones can move onto the wheels but the batt not have enough power to move the c/van and the mover is then stuck against the wheels ,(so we have the manual version) 

Ours  came with a tool so you can manually wind them off if necessary.