Which device allows customers to input their PIN securely?

The device that allows customers to input their PIN securely is the PIN pad. This is specifically designed for the secure entry of personal identification numbers during electronic transactions. PIN pads have features that ensure the privacy and security of the PIN being entered, such as physical shields or privacy screens, numeric keypads designed for easy use, and often encryption capabilities to protect the data as it is transmitted.

In contrast, other devices such as check readers, contactless readers, and payment terminals do not focus on secure PIN input. A check reader primarily processes checks and doesn't involve PIN entry. A contactless reader enables transactions through technologies like NFC (Near Field Communication) without the need for entering a PIN, especially for low-value purchases. A payment terminal encompasses various capabilities, including accepting card payments and processing transactions, but not all payment terminals are equipped with dedicated PIN input features, which are specifically addressed by PIN pads. Thus, the unique design and purpose of the PIN pad make it the correct choice for securely inputting a PIN.