Uni-Ball Signo RT1 UMN155-05 Gel Ink Rollerball Pen 0.5mm Blue/Black Box of 10
Uni-Ball Signo RT1 UMN155-05 Gel Ink Rollerball Pen 0.5mm Blue/Black Box of 10
Uni-Ball Signo RT1 UMN155-05 Gel Ink Rollerball Pen 0.5mm Blue/Black Box of 10
Uni-Ball Signo RT1 UMN155-05 Gel Ink Rollerball Pen 0.5mm Blue/Black Box of 10
Uni-Ball Signo RT1 UMN155-05 Gel Ink Rollerball Pen 0.5mm Blue/Black Box of 10
Uni-Ball Signo RT1 UMN155-05 Gel Ink Rollerball Pen 0.5mm Blue/Black Box of 10
Uni-Ball Signo RT1 UMN155-05 Gel Ink Rollerball Pen 0.5mm Blue/Black Box of 10
Uni-Ball Signo RT1 UMN155-05 Gel Ink Rollerball Pen 0.5mm Blue/Black Box of 10
Uni-Ball Signo RT1 UMN155-05 Gel Ink Rollerball Pen 0.5mm Blue/Black Box of 10
Uni-Ball Signo RT1 UMN155-05 Gel Ink Rollerball Pen 0.5mm Blue/Black Box of 10
Uni-Ball Signo RT1 UMN155-05 Gel Ink Rollerball Pen 0.5mm Blue/Black Box of 10
Uni-Ball Signo RT1 UMN155-05 Gel Ink Rollerball Pen 0.5mm Blue/Black Box of 10
Uni-Ball Signo RT1 UMN155-05 Gel Ink Rollerball Pen 0.5mm Blue/Black Box of 10
Uni-Ball Signo RT1 UMN155-05 Gel Ink Rollerball Pen 0.5mm Blue/Black Box of 10
Uni-Ball Signo RT1 UMN155-05 Gel Ink Rollerball Pen 0.5mm Blue/Black Box of 10
Uniball

Uni-ball Signo RT1 UMN155-05 Retractable Gel Ink Rollerball Pen 0.5mm Blue/Black Box of 10

$22.46
$22.46
RRP $23.87
Or 4 payments of $5.62 with
Add items to a quote for bulk pricing, approvals, or purchase orders.

SKU: UMUMN155-05BB

UPC: 4902778142769

MPN: UMN155-05BB

Blue/Black, the Colour Between the Two Standards

Blue/Black is the compromise colour in the uni-ball Signo RT1 range, a retractable gel ink pen published at a 0.5mm line width in uni-ball's 2026 catalogue.

Blue/black exists because the two standard office colours each have a drawback. Pure black gives nothing away about whether a page is an original. Bright blue can look informal on a formal document. A blue/black reads as near black across a page of text while staying visibly blue up close, which is why it has been the traditional choice for ledgers and formal correspondence.

The pen is retractable, which uni-ball states for this model, so there is no cap in the equation. uni-ball publishes the ink as gel ink and the group code as UMN-155, with this width written UMN155-05 on uni-ball's own site. A box of 10 is the ordering unit, all one colour.

The plain black and plain blue versions are both at gel pens, alongside the 0.38mm width of the same pen. The brand range sits at uni-ball, with other pens at pens.

Often ordered together

  • Retractable, as published by uni-ball for the Signo RT1
  • Gel ink, described on uni-ball's own page as new improved gel ink
  • 0.5mm line width, published in uni-ball's 2026 product catalogue rather than on the product page
  • Blue/black ink, reading near black on the page and blue up close
  • uni-ball publishes the model under the group code UMN-155, this width as UMN155-05
  • Supplied as a box of 10, all one colour
  • Formal correspondence and letters
  • Ledgers, registers and record books
  • Signing where an original must be distinguishable
  • Professional and client-facing note-taking
  • Executive desk and boardroom pen sets

Shipping

Shipping is kept simple with flat rates for selected areas and free shipping where applicable. Large, bulky, rural or out-of-area orders may require additional freight, and our team will contact you if this applies. For a more specific estimate, simply add this product to a quote or visit our shipping page.

Delivery Times

Melbourne, Sydney, Brisbane, Adelaide — 1 to 3 business days
Perth — 1 to 5 business days
Regional & Outer Areas — 3 to 7 business days

Returns

If you have questions about returns, please contact us or visit our returns page for full details.

Specifications

Brand: uni-ball

Range: Signo RT1

Model Group: UMN-155

Manufacturer Code: UMN155-05

Mega Code: UMUMN155-05BB

Colour: Blue/Black

Line Width: 0.5mm (published in uni-ball's 2026 product catalogue, not on the product page)

Ink Type: Gel ink

Mechanism: Retractable

Pack: Box of 10

Barcode: 4902778142769

Refill Code: Not published by the manufacturer

Country Of Origin: Not published by the manufacturer

Primary Distribution Centre

Factory 5, 12 Greenway Drive
Tweed Heads South NSW 2486

ABN 18 634 002 609

Get directionsContact us

FAQs

uni-ball's product page for the Signo RT1 does not publish a tip size. The 0.5mm figure is published in uni-ball's 2026 product catalogue, which lists the model in three widths. We have attributed it to the catalogue rather than the page so you can see which source it rests on.
uni-ball publishes no refill code for the Signo RT1, so we are not going to name one. Other Signo models take their own specific refills and guessing across models is how the wrong cartridge gets ordered. Ask us and we will chase the code through the supplier.
On the page a blue/black reads much closer to black, while a plain blue reads plainly blue. The practical use is formal paperwork where you want the document to look black but still be identifiable as handwritten in ink. uni-ball does not publish colour names as text, so this description is ours, not uni-ball's.
Retractable. uni-ball states that on its own product page for this model, which is why we are comfortable publishing it. There is no cap.
uni-ball is not consistent about it. The uni-ball website publishes this width as UMN155-05, while uni-ball's 2026 catalogue uses a different pattern for the family, writing the finer 0.38mm pen as UMN-155-38. The two sources do not spell the range the same way, so we have used the website spelling and flagged it rather than picking one silently.
Ten, all blue/black. That is the pack we hold against UMUMN155-05BB, read from this product's own record rather than assumed from the range.

Shipping & Delivery

Delivery time depends on your location, the size of your order, and the shipping option selected at checkout. For in-stock items, standard metro delivery in QLD, NSW and VIC is usually 1 to 7 business days. South Australia, Tasmania, Western Australia and the Northern Territory are generally 3 to 12 business days. Express delivery for eligible parcels under 3kg is usually 1 to 4 business days in QLD, NSW, ACT and VIC. Delivery estimates apply to in-stock items only and may vary due to carrier conditions or delays.

If you need to make a change to your order, please contact our team as soon as possible. Once an order has been processed or dispatched, changes may no longer be possible. You can contact us through our Contact Us page for assistance.

Mega Office Supplies ships orders Australia wide and occasionally internationally. The best avenue would be to contact us so we can customise a specific quote for you. Please note that associated international duties, taxes and levies will be the responsibility of the customer.

Returns, Refunds & Replacements

Mega Office Supplies accepts change-of-mind returns for unopened and unused products within 14 days from the invoice date, provided the item is returned in its original packaging and in resalable condition. Original shipping costs are not refundable, return shipping is the customer’s responsibility, and a restocking fee may apply depending on the product type and supplier. Some items, including electronics, assembled or installed furniture, food, beverages, medicines, custom-made products, and certain bulk or special-order items, are not eligible for return unless required under Australian Consumer Law.

If your order arrives faulty, damaged, or incorrect, please contact Mega Office Supplies as soon as possible. Where required under Australian Consumer Law, a repair, replacement, or refund will be offered. In these cases, Mega Office Supplies will cover reasonable return shipping costs, and photographic evidence may be requested to help process the claim. Items should be reported within a reasonable timeframe after delivery.