Name: Harris & Lockyer Keyboard more
Manufacturer: Harris & Lockyer Associates
Price: £26.95
Blurb: Bare keyboard without a case. Presumabley they sit on top of the computer. Keyswicthes and a spacebar.
Source: Sinclair User Oct 82

Name: Haven I/O more
Manufacturer: Haven Hardware
Price: £16.95
Blurb: I/O ports. 8 input and 8 outputs.
Source: ZX Computing Dec/Jan 84

Name: Haven Keyboard Beeper more
Manufacturer: Haven Hardware
Price: £8.90
Blurb: Emits a beep when any key is pressed. [why? you can do the same with POKE 23609,x]
Source: Sinclair User Jan 83

Name: Haven Single Key Input more
Manufacturer: Haven Hardware
Price: £4.95
Blurb: Small board that is soldered inside the Speccy that eliminates the 'keyword' feature, instead giving single letter entry.
Source: Sinclair User Jan 83

Name: Heart Rate Monitor more
Manufacturer: Magenta Electronics Ltd
Price: £29.98
Blurb: Monitor your heart rate via your finger tips. Place fingers over pads and the unit will do the rest.
Source: Sinclair User Sep 83

Name: Hilderbay Interface more
Manufacturer: Hilderbay Ltd
Price: £45.00
Blurb: Centronics printer interface with software. Supports all printer commands.
Source: ZX Computing Aug/Sep 83
Note: Came with a software tape: Hilderbay Printer Program.

Name: Hilderbay Tape-Aid more
Manufacturer: Hilderbay Ltd
Price: £5.95 / £7.95
Blurb: Cure tape loading problems with this interface. Stop drop-outs and load even poor quality tapes. Deluxe version (£7.95) has a larger meter.
Source: Sinclair User - Mar 83

Name: HiLow more
Manufacturer: HiLow Computers
Note: A High Speed Digital Cassette Drive, which also has NMI capabilities, allowing you to dump the contents of the machine to tape.

Name: Hobbyboard Intelligent Joystick Interface more
Manufacturer: Hobbyboard
Price: £20.80
Blurb: Supplied in kit form, this was a standard programmable interface.
Source: ZX Computing Apr/May 84

Name: Hobbyboard Micro Interface more
Manufacturer: Hobbyboard
Price: £9.50
Blurb: Hobbyboard offered build-yourself kits to produce things like light pens, digitisers and model controllers. This interface was to 'professionalise' your kits.
Source: ZX Computing Apr/May 84

Name: HyperShot more
Manufacturer: Konami Ltd
Price: £9.95
Blurb: Joypad with twin button. Aimed at sports sims like Hypersports it has buttons similar to the arcade machine.
Source: Your Spectrum issue 18