With strong button and 4 thickened pressure suction cups. By tightening the screw cap, the air is squeezed out more cleanly. Strong suction cups ensure that the hammock is safer and more durable. As for the suction cup of the button, first loosen the button, then press the suction cup against the glass and tighten the button until it is no longer tightened. the frame is made of high-strength fibreglass tubes and the load capacity can reach 23 kg. The sturdy steel rope not only prevents cats from biting through, but also has a stronger load capacity so your cat can jump in and out of the cat hammock. It is recommended to re-attach the cat hammock from time to time to prevent air from entering the suction cups and it falls off during prolonged use.