UI Kits are those elements of design which are responsible for the user interface of any applications. Buttons, info boxes, text fields, input fields, dropdowns, progress bars, I`m sure you know them all and I`m sure you`re seeing them everyday in apps like online email services as gmail, yahoomail, etc, admin panels, or any website you`re surfing on, but I want to present you another 40 amazing UI kits available in PSD format, which are free to download and use!