The Model A STP is a larger STP and measures 5.5 in (14cm) from the top lip to the tip of the head. The Model A STP has a sturdy receptacle cup that is easy to use and requires no flow control.

Made of a Soft Powder Finish Platinum Silicone to help reduce chafing and the tacky feeling of silicone, the Model A STP has a clean, soft to the touch 'skin' texture.