Thank you for your question. The gray PEX supply lines of the Delta Classic Lavatory faucet 521-DST-A are apart of the faucet valve. Theses lines are not removable or replaceable. However, the PEX supplies can be cut to fit for an installation, below are the installation directions showing that type of installation (pages 5 and 6, module 2).
Date published: 2016-09-28