There are three approaches to the problem of height selection: 1) Very basic height selectors, 2) television monitors and 3) Lasers.

The first of these has many limitations, not least their inability to cope with floor variations, tyre wear, (which could be as much as an inch or more) without recalibration. TV monitors, apart from the high expense, are notoriously prone to damage and breakdown. It is not uncommon for users to stop using them after just a few weeks. The most reliable, safest and cost effective is the laser height selector, which copes with all the aforesaid problems without needing any recalibration. A leading company in this field is Lacey-Harmer Co, of 4270 NW Yeon Ave, Portland, OR 97210, USA. (Phone: (503 222-97210 or email: [email address removed]