Aside from doing some very sexy due diligence as a classic collar and leash, this duo looks downright dreamy. Wrap the Collar around a neck in question before tightening up the simple buckle band. Clip the long chain leash to a sturdy D-ring placed dead-center.
In synthetic vegan leather (PU) with nickel free hardware, the Spectra Collar & Leash should be spot cleaned as needed. You can use a favorite toy care fluid/foam, or warm soapy water for easy clean-up. 
* The Spectra Collar fits up to about 8"/20.32cm of neck diameter. The Leash is about 37"/94cm long, including the handle