Need help with twin slot shelving!

twin slot shelving systems   Dan twin slot shelving kit

I have used this shelving system before and never had a problem

Does anyone know if twin slot shelving is a standard ? I have some brackets from B&Q but they didn't have the tracks in stock Screwfix do but Our Rectangular Twin Slot Chrome Uprights combine strength with versatility to give you a quick and easy retail shelving system Create a stunning retail

remove door knob with no screws or slot Product Detail The Twinslot Shelving system is designed as a simple 'upright & bracket' arrangement, for supporting various types of timber shelves  Twin slot shelving system brackets uprights QTY: 1 pc Upright sizes: L951mm, W25mm, T12mm Bracket sizes: - 170mm