Lloyd Loar, like Orville Gibson before him, took design principles from the violin family and applied them to mandolins and guitars. He designed the first guitar with F-holes instead of a round sound hole, the L-5. He applied the same princliple to the F-5 mandolin, which has become the standard design used in Bluegrass music.
The Gibson L-5 has been in production in various variations since its introdcution in 1922. Among famous guitarists to play an L-5 are Wes Montgomery, Scotty Moore, Lee Ritenour, Pat Martin, Tuck Andress, Maybelle Carter and briefly Django Reinhardt.