| 541 | Level Controller | Company Product |
| 542 | Level Controllers - Conductive Liquids | Company Product |
| 543 | Level Controls | Company Product |
| 544 | Level Detection | Company Product |
| 545 | Level Electrodes | Company Product |
| 546 | Level Float Switches | Company Product |
| 547 | Level Floats | Company Product |
| 548 | Level Gauge | Company Product |
| 549 | Level Gauge Explosion Proofs | Company Product |
| 550 | Level Gauge Illumination Devices | Company Product |
| 551 | Level Gauges | Company Product |
| 552 | Level Indicators | Company Product |
| 553 | Level Loader | Company Product |
| 554 | Level Measurements | Company Product |
| 555 | Level Meters | Company Product |
| 556 | Level Monitor | Company Product |
| 557 | Level Probe | Company Product |
| 558 | Level Recorders | Company Product |
| 559 | Level Sensors | Company Product |
| 560 | Level Switch | Company Product |
| 561 | Level Switches | Company Product |
| 562 | Level Transducers | Company Product |
| 563 | Level Transmitters | Company Product |
| 564 | Leveling Bush | Company Product |
| 565 | Leveling Jack | Company Product |
| 566 | Leveling Rod | Company Product |
| 567 | Leveling Valve | Company Product |
| 568 | Levelling | Company Product |
| 569 | Levelling Agents | Company Product |
| 570 | Levelling Base | Company Product |