This does not require the use of tools for assembly nor removal of the seat from the existing standard height toilet. However to get it tight enough to bear snugly and avoid wobbling, the knob must be tightened very snugly with a pliers; there is simply not enough strength in ones's fingers to make it tight enough to be immovable. Also when mounting both hands should be used simultanously and sit back up against the foldedup seat. This is not a jungle jim or a kiddy toilet so it will pop out if all your weight is on one arm. I would not recommend the armless model unless you have one of those safety frames resembling a large walker. The length is four inches less than a standard toilet so the large male will find it uncomfortable at least to stuff himself in. The water does't reach the appliance so rinsing and wiping must be done by the user. The large male is advised to sit on the edge and hold a safety or regular urinal in front of himself, thus avoiding squeezing and failure to void or unsanitary dribbling. On need only pull down one's clothing to the knees to use this successfully. All in all, convenient, and portable, and much cheaper than a plumber-installed porcelain toilet. Comparable in size to the toilet on a train, a bus, or airliner; no wide legged posture possible.