Bulkhead fittings are used to attach PVC pipes to aquariums and sump filters for uses such as drains and overflows. For aquarium plumbing projects, high quality bulkhead fittings that don’t crack and break are a must. The slip by slip (non-threaded) bulkhead fittings from Aquarium Co-Op are designed to withstand wear and tear without breaking down over time. They can even be used outdoors as they are extra thick and stabilized to hold up in the sun and elements. The tapered ends allow for easy fitting onto any pipe brand.