Here's a diagram of the A7LB suit used on Apollo 15 through 17. Modified versions of this suit were used on the Skylab missions.

The Apollo Experience Report: Development of the Extravehicular Mobility Unit has additional information on both the A7L and A7LB suits.

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From p. 7-19 (p 170 in the PDF) of Application of EVA Guidelines and Design Criteria. Volume 1: EVA Selection/Systems Design Considerations
Extraction and cleanup by heroicrelics.

Lunar Extravehicular Visor Assembly (LEVA)

During lunar surface and deep space EVAs, astronauts wore a Lunar Extravehicular Visor Assembly, or LEVA, over their pressure helmet assembly ("bubble" helmet). The LEVA provided visual, thermal, and mechanical protection to the astronaut's helmet. It was composed of a plastic shell, three eyeshades (left, center, and right), and two visors. The outer visor (sun visor) was made of high-temperature polysulfone plastic. The inner visor (protective visor) was made of ultraviolet-stabilized polycarbonate. The outer visor filtered visible light and rejected a significant amount of ultraviolet and infrared rays. The inner visor filtered ultraviolet rays and rejected infrared rays. Together, they formed an effective thermal barrier.

The two visors, in conjunction with the helmet, protected the astronaut from micrometeoroids and from damage during possible falls on the lunar surface.

The sun visor and eyeshades could be individually positioned anywhere between "full up" and "full down" but the protective visor was intended to be worn in the "full down" position during extravehicular operations.

The LEVA could be installed or removed without tools. A latching mechanism allowed the lower rim of the LEVA to be tightened and secured around the neck area of the bubble helmet.

The LEVA/PGA interface collar provided thermal and dust protection for the neck ring.

Click image for a 4106x5331 pixel version of this image in a new window.
From p. 4-316 of Maintenance Manual, Model A7LB, Apollo, Skylab & ASTP Space Suits, Volume 1 in the private collection of Mark Wells.
Scan and cleanup by heroicrelics.

This general style of LEVA was worn on Apollo 13 through Apollo 17. Earlier LEVAs were similar, but various mechanical and optical improvements were implemented in later revisions of the visor assembly. In particular, the models used on earlier missions lacked the center eyeshade and had less refined side sunshades.

The Apollo Lunar Surface Journal contains additional information regarding the LEVA.