Offering 4.0x magnification as standard, 26mm (1.0x), 80mm (4.0x) and 120mm (6.0x) lenses are available as optional extras. The built-in Infrared (IR) Illuminator has a variable beam setting allowing it to be focused from flood to spot so that it can be used with all lens options.

The Merlin 100™ can also be fitted with an optional headmount with the 26mm (1.0x) lens so that it can be used as a hands-free night vision goggle (NVG).

Latest accessory options include an IR Adaptor, so that optional 75mW and 150mW high power IR Illuminators can be attached. A choice of two Day Scope Adaptors is also available for use with the 26mm lens, the HDSA™ (Hinged Day Scope Adaptor) and DSA™ (Day Scope Adaptor), so that the unit can be attached to a day telescopic sight thus turning it in to a night vision unit.