When you’re enthusiastic about switching your halogen downlights to LED, you might be able to just replace the bulb, but in selected conditions, you’ll really need to replace the bulb’s power source. Pull out the existing halogen light. MR11 and MR16 lights have pins that thrust straight into your fitting, https://docs.google.com/spreadsheets/d/1QuLrdtwC6wLNTkOTKDc0E0Te3Zuz6kJxFzyKESC1XXk