Add to cart Quick Connect Elbow Check Valve 1/4 to 1/8 inch Male BSP $4.98 The Quick Connect Elbow Check Valve 1/4 to 1/8 inch Male BSP allows you to connect the 1/4 inch Polyethylene RO tubing to a 1/8 inch female fitting at a 90 degree angle. The built in check valve ensures water will flow in one direction from the quick connect to the male BSP side. Add to Wishlist