A gypsy is basically a nautical sprocket; it handles chain through the use of internal pockets which the chain links seat into. Obviously, the size chain must be compatible with the size pockets of the gypsy. The chain and the pockets must be identical, or the chain will hang up.
Vertical windlasses are installed with the motor and gearbox mounted below deck. This leaves the foredeck relatively uncluttered, unless you choose the capstan option mounted above the gypsy. Vertical windlasses are versatile, as the rode can be led from any direction. The rode wraps around the drum/gypsy through 180°, and leads forward to the hawse pipe and down into the chain locker.