Parker Hannifin Hose Fittings51 Series Reusable Hose Fitting Socket x 1/4" i.d. Hose. Fitting Series: 51 SeriesParker Parflex specializes in the design and production of hose, tubing, and accessories made from thermoplastic and fluoropolymer materials, providing unique solutions for various applications.Next Day Fittings is an official Parker distributor, we can offer our customers the best pricing and factory lead times. Our trained and knowledgeable staff is always ready to help with any aspect of the Parker Hannifin product purchasing process. Whether you need assistance from a customer service agent or a product engineering expert, Next Day Fittings is your Parker partner every step of the way.