At IDEX-2013, China revealed a scaled-down version of Type 039A submarine designated as S20, specially intended for export. The main difference between S20 and Type 039A is that the AIP system on the original Type 039A is deleted, but can be available and easily integrated due to modular design of S20, if potential customers choose to purchase AIP systems separately. Due to its modular design, a variety of sensors and weapons can also be easily adopted up on customers' requests.[9] Specifications of S20:[10]