Each kit or mod package contains the electronic components relevant to the circuit. For example, the GPK Guitar Preamp Kit contains the electronic components that make up the audio path of a guitar preamp. This does not include the power supply components or the switching components. For those circuits, extra kits are required (13VA and ERK respectively).

Power management kits, switching circuits and power supplies have a layout drawing to make either an eyelet board or a perf-board. Kits with larger parts (like the power supplies) or that have parts on which the leads can be splayed out (as in the ERK) can be built using eyelet boards. Kits with tight-spaced component leads, such as the integrated circuit in the QRK, come with a perf-board layout. Perf-board has 40-mil holes on a 0.1" grid, ideally suited to mounting semiconductors.

Kits to build preamps and power amps have two eyelet-board layout drawings. One drawing allows the tubes and components to be on the same side of the card, for applications where the tubes will be inside the chassis. The second layout allows the tubes to be outside the chassis while the card and other components are inside the chassis.

The DC Power Scale kits all come with printed circuit boards. In the course of 2008, all of the kits will acquire PCBs.

Modification packages supply only the "extra" components that must be added to an existing circuit to change or enhance its function.

The components used in the kits are the same ones London Power uses in their amplifier and sound accessory products. This includes: metal-film precision resistors, flame-proof metal-oxide resistors, high-quality plastic capacitors, low-leakage long-life-high-temperature electrolytics, custom toroidal power and output transformers, and safety-agency approved mains elements (fuse-holders, switches). Semiconductors and tubes are used well within their ratings.

There is no warranty on kits or the parts contained in them. Every effort has been made to assure the kit notes are error-free. London Power is not responsible for misinterpretation of kit notes, mis-installation, or for any damage such errors may cause.