Dear friends, thank you very much for liking our products. All the marked product dimensions are the dimensions of the cylinder inner diameter. All products are made of molds, so there is a slight error between each product. The error range of each product is 1-3mm. How Do Pump Traction Devices Work?     This gentle ，painless stretching causes the cells within the corpora cavernosa to pull away and split.Just like muscle buliding,during the cell healing process,healthy new cells are created,allowing your penis to become larger.And with a bigger corpora cavernosa,your penis can hold more blood,meaning you'll also enjoy bigger and harder erections! Instructions for use Lubricate the inner wall of the cylinder and yourself.     Insert your penis into the cylinder. The cylinder should remain firmly pressed against the base of your penis to keep air from escaping.     Slowly begin to work the pump. There will be a slight sensation as air is drawn from the cylinder. For beginners, it is important to start this process slowly to avoid discomfort. Remember to press the safety release valve if the vacuum becomes painful.     Continue pumping/releasing air until you've found a level of vacuum suitable for you: the penis should look swollen, but should not hurt.     Now make sure no air escapes (unless needed) and wait 20 minutes. You may need to pump further during this time to keep an appropriate amount of vacuum in the cylinder.     Once the session is complete, you should appear thicker/longer and have heightened sensitivity. These results are effective for 24 hours, but you may experience permanent results through long-term use. We recommend 3-4 sessions per week. USB charging penis pump     The electric pump uses a USB charging suction handle to complete suction and deflation. Please read the user manual when using the electric handle. Manual Penile Pump Pressing the black button will release the air pressure Changes in the penis Penis enlargement pump sizes     Acrylic Model A1：4.4-22.9cm/1.75-9inch  ;Acrylic Model A2：5.1-22.9cm/2-9inch     Acrylic Model A3：5.7-22.9cm/2.25-9inch ;Acrylic Model A4：6.3-22.9cm/2.5-9inch     Acrylic Model A5：4.4-30.5cm/1.75-12inch ; Acrylic Model A6：5.1-30.5cm/2-12inch     Acrylic Model A7：5.7-30.5cm/2.25-12inch  ; Acrylic Model A8：6.3-30.5cm/2.5-12inch     The sales link not only includes the complete set of products, but also includes independent cylinder accessories. Please pay attention to differentiation when purchasing. The electric x.x-xx. x cm is a complete set of electric versions of the product; Manual x.x-xx. x cm is the complete manual version of the product; The x.x-xx. x cm cylinder is a separate cylinder accessory.Model D is a separate D model soft silicone gasket. Soft elastic silicone gasket Model A: Small size soft silicone gasket with elasticity, suitable for acrylic cylinders of 4.4cm(1.75inch ). Model B: Small size soft silicone gasket with elasticity, suitable for acrylic cylinders of 5.1cm(2.0inch ). Model C: Large size flexible silicone gasket with elasticity, suitable for acrylic cylinders of 5.7cm(2.25inch) and 6.3cm（2.5inch）. Model D gasket: model D belongs to large aperture soft silicone gaskets, suitable for huge penises with a width exceeding 5.6cm/2.20inches. Only a small number of customers need it, and if you need Model D soft silicone gaskets, you need to purchase them separately.     Silicone gaskets have elasticity and are made of a soft and durable material. The width of the penis needs to be greater than the aperture of the soft silicone gasket. A soft silicone gasket can be placed on the penis to create a sealing space. The material is made of environmentally friendly acrylic blocks, which can be used with confidence Product detail presentation Easy  Release  Connector  Instructions     1.To connect the tubing,press and twist the connector at the end of the tube.     2.When you hear the click,the tubing is fully inserted.     3.To remove,push the metal tab inward and pull the tubing at the base.Youcan remove the tubing and pump while maintaining pressure in the cylinder. The acrylic tank comes with a seal switch, after removing the link pipe can still maintain negative pressure. About the package: send privately 1.WORLDWIDE SHIPPING. (Except some countries and APO/FPO) 2. Orders processed timely after the payment verification. 3. We only ship to confirmed order addresses. Your order address MUST MATCH your Shipping address. 4. The images shown are not the actual item and are for your reference only. 5. If you have not received your shipment within 45 days from payment, please contact us. We will track the shipment and get back to you as soon as possible with a reply. Our goal is customer satisfaction! About payment: Buyer pays tutorial below: https://service.aliexpress.com/page/knowledge?pageId=37&category=1000021991&knowledge=1060062451&language=en