Articles Related to: MR11
Replacing Halogen Lamps With LED Spotlights
So what actually is an MR16 lamp? The prefix MR stands for Multifaceted Reflector and the suffix 16 is the diameter expressed in eights of an inch, so 16/8 is 2 inches across at its maximum width. The mr11 format is thus basically the same but quite a bit smaller.
The reflector is what controls the beam angle and color of the light from the lamp, and a multifaceted reflector has small dimples (facets) which result in a much softer light and reduces harsh contrasts. Note however that it is possible to obtain MR16 and mr11 lamps that have smooth (non-faceted) ... LED Garden Lighting Basics
Nor is there anything really to stop you using standard indoor 12 volt LED light bulbs as part of the outdoor lighting system. If any of your outdoor fittings accept a bi-pin lamp base (as commonly found on G4 capsules and mr11 spots for example) then you're in business.
An LED on it's own is not much good in a garden though - you need to mount it in something, preferably a fixture designed for the garden in the first place such as a spike or spot light for example. The easy route is to cannibalize old, cheap or non-functioning regular halogen fixtures since these will have the right sort of ... 
