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Ferrule crimper or insulated terminal crimper

Updated: 21 October 2026

You are holding either a thin metal sleeve with a coloured collar, or a red, blue or yellow ring, spade or butt. Both are called a crimping pliers set. They are not the same jaw. This page is which die matches the terminal in your hand. Prices sit on the [crimping pliers set comparison](/hub/pliers/crimping-pliers-set). A qualifying purchase can earn us a commission at no extra cost to you. A ferrule die crimps a tube. An insulated-terminal die crimps a barrel and its sleeve. Using either on the other terminal leaves a loose joint.

You are holding either a thin metal sleeve with a coloured collar, or a red, blue or yellow ring, spade or butt. Both are called a crimping pliers set. They are not the same jaw.

Our top picks

Preciva Preciva ferrule crimper set, 1,200 sleeves

Best overall

Preciva Preciva ferrule crimper set, 1,200 sleeves
9.4/10about £22.99
View offer
Preciva Preciva insulated terminal kit, 370 pieces

Alternative

Preciva Preciva insulated terminal kit, 370 pieces
9.2/10about £22.99
View offer
Hibisaws Hibisaws ferrule kit, 1,250 sleeves

Best value

Hibisaws Hibisaws ferrule kit, 1,250 sleeves
9.0/10about £19.99
View offer
On this page
  1. 1.What each jaw is crushing
  2. 2.How the colours diverge
  3. 3.Which kits in this comparison are which
  4. 4.Which to buy for the terminal in your hand

What each jaw is crushing

A bootlace ferrule is a short tube. A square or six-sided die closes it around fine strands. RS’s crimp-tools guide says the tool crimps the metal tube, not the coloured collar, so a ferrule die has no insulation nest. An insulated ring, spade or butt has a barrel and a plastic sleeve. The three-colour nest closes that barrel without slicing the sleeve. IET EngX calls that nest the wrong ferrule die. A bootlace in a red nest nicks the collar or leaves the tube round. A ring in a square jaw can split the insulation. Either joint can look finished and still slide. Whether a ferrule belongs at all is the bootlace ferrules and BS 7671 page.

How the colours diverge

Red, blue and yellow on an insulated terminal are a size band: red 0.5–1.5 mm², blue 1.5–2.5 mm², yellow 4–6 mm², with overlap by maker. The Preciva and Grasomtools nests in this comparison are marked that way. Ferrule collars follow DIN 46228-4, a French code, or a code UK sellers call German. Those do not line up with the three ring colours. A green ferrule is not the yellow one. Read the printed mm². A self-adjusting die across 0.25–10 mm² does not make the two colour systems match.
Preciva Preciva ferrule crimper set, 1,200 sleeves

Testsieger

Preciva Preciva ferrule crimper set, 1,200 sleeves
9.4/10about £22.99
View offer

Which kits in this comparison are which

Ferrule rows are the Preciva CP621200, the Hibisaws HSC8 6-4, the Preciva twin-sleeve kit and the AivaToba tool to 16 mm². Buy them for a cord-end sleeve, not a trailer-plug ring. Insulated rows are the Preciva RC50371, RC35147 and RC60003, plus the Grasomtools GR30J. Those are three-colour nests for 0.5–6 mm². Do not buy them for a bootlace. Only the Preciva six-head set at £42.99 claims both, by swapping heads, and a professional review says the heat-shrink splices pulled out. The Proster RJ45 kit is neither side. The sleeve stroke is on how to crimp a bootlace ferrule.

Which to buy for the terminal in your hand

If the terminal is a bootlace sleeve in a screw terminal, buy a ferrule row. The Preciva CP621200 at £22.99 is the strong 0.25–10 mm² pick. The Hibisaws kit at £19.99 is the cheaper same job if you will refit the handle cover. If it is a red, blue or yellow ring, spade or butt, buy an insulated row. The Preciva RC50371 at £22.99 has the strongest star line in that family, and a live complaint about yellow terminals. More pieces do not turn a ferrule kit into a ring tool. If you do both jobs a few times a year, the six-head Preciva is the only listing that claims both. Read the heat-shrink review before £42.99. An RJ45 plug is neither die. The wider choice is the crimping pliers set buying guide.

Common questions

Can I crimp a bootlace with a red, blue and yellow tool?
No. That nest is cut for an insulated barrel and its sleeve. IET discussion and the RS guide both treat it as the wrong ferrule die. The tube will not close as a square or hex crimp, and the collar can split.
Can I crimp a ring terminal with a square ferrule jaw?
No. A ferrule die has no insulation nest. The plastic sleeve can split and the conductor barrel may stay round. Use a three-colour insulated kit for rings, spades, bullets and butts.
What are the three colours on an insulated terminal?
In the usual UK shop code, red is 0.5–1.5 mm², blue is 1.5–2.5 mm² and yellow is 4–6 mm², with overlap by brand. Read the printed band on the nest and on the terminal, not the colour of a nearby ferrule.
What does a square crimp change?
On a bootlace, a square or six-side die closes the tube on four or six sides so the strands stay as one pin. It is not a better ring crimp. An insulated nest is a different shape for a different barrel.
Which listing in this comparison does both?
Only the Preciva six-head set, by swapping jaws, at £42.99. A professional review says the heat-shrink splices pulled out. Every other kept kit is one family or the other, plus one RJ45 tool.
Are ferrule collar colours the same as red, blue and yellow?
No. Ferrule sequences disagree with each other and with the insulated-terminal code. Printed mm² is the size. Colour is a sorting aid inside one maker’s pack.
What should I buy if I do both jobs twice a year?
Either the six-head Preciva if you will change jaws and skip the heat-shrink head, or one ferrule kit plus one insulated kit. Two single-purpose ratchets can still be clearer than one frame you have to reconfigure on the bench.

Related pages

Ferrule pliers

Crimping pliers set

Best crimping tool kit for ferrules, rings or plugs

Bootlace ferrules and BS 7671 for fine stranded flex

Crimping pliers set buying guide for household kits

How to crimp a bootlace ferrule without a half-cycle

Sources

Public UK sources from the research digest, last checked on 19 October 2026. Shelf prices and star lines are the amazon.co.uk figures in the display file.

  1. IET Wiring Matters: Mythbuster 5, terminal blocks and ferrules (retrieved 19 October 2026)
  2. IET EngX: Ferrule crimps (retrieved 19 October 2026)
  3. IET EngX: Crimping of flexible cord conductors (retrieved 19 October 2026)
  4. BSI: BS 7609:1992+A2:2009, uninsulated power connectors (retrieved 19 October 2026)
  5. HSE: Electricity at Work Regulations guidance, HSR25 (retrieved 19 October 2026)
  6. RS: Bootlace ferrules (retrieved 19 October 2026)
  7. RS: Knipex 97 53 04 crimp tool (retrieved 19 October 2026)
  8. Klauke GB: Insulated solderless terminals (retrieved 19 October 2026)