Other than covering your neck area with a removable bib/guard, it is possible to use to increase the protection required for your neck, with the mask not follow covering this dangerous area. The dangler is attached to the helmet or mask, hanging off the chin of the helmet, to cover the open neck area and provide suitable protection against a potential shot there.
There are field hockey specific types of danglers mass produced by a number of companies, like Grays, Obo or TK, that can be attached to the helmet, fixing on below the chin area. Made of pvc, they are strong enough to withstand the majority of shots to the neck area; offering a flat blocking shape against balls ending up between the helmet and body armour. However, they should really only be used in conjunction with helmet/cage combos, as the plastic dangler can attach to the helmet without it moving around wildly; if you tried to attach it to a mask, then it will not make efficient connection, leaving you open to shots as you move around, as it swings up.
Ice hockey danglers
Ice hockey companies mass produce lexan danglers for their goaltenders, which attach around the mask’s chin to offer all-round protection to the throat. These can be used by us field hockey goalies to cover the open space below the mask chin; covering your voice box and neck from possible harm. The dangler is made of strong composite materials which are capable of absorbing a shot (really hard shots could crack it and will obviously need replacing!). You can get different danglers to suit the type of helmet; larger round danglers are suitable for both helmet/cage combos and masks, providing a wide rim of protection, whilst the smaller V-shaped danglers work OK with masks, offering a tighter area of coverage; the shape not interfering with the chin.