Uni Signo RT1 Gel Ink Pen Ultra Fine 0.38mm Blue Black Box of 10
Uni Signo RT1 Gel Ink Pen Ultra Fine 0.38mm Blue Black Box of 10
Uni Signo RT1 Gel Ink Pen Ultra Fine 0.38mm Blue Black Box of 10
Uni Signo RT1 Gel Ink Pen Ultra Fine 0.38mm Blue Black Box of 10
Uni Signo RT1 Gel Ink Pen Ultra Fine 0.38mm Blue Black Box of 10
Uni Signo RT1 Gel Ink Pen Ultra Fine 0.38mm Blue Black Box of 10
Uni Signo RT1 Gel Ink Pen Ultra Fine 0.38mm Blue Black Box of 10
Uni Signo RT1 Gel Ink Pen Ultra Fine 0.38mm Blue Black Box of 10
Uni Signo RT1 Gel Ink Pen Ultra Fine 0.38mm Blue Black Box of 10
Uni Signo RT1 Gel Ink Pen Ultra Fine 0.38mm Blue Black Box of 10
Uni Signo RT1 Gel Ink Pen Ultra Fine 0.38mm Blue Black Box of 10
Uni Signo RT1 Gel Ink Pen Ultra Fine 0.38mm Blue Black Box of 10
Uni Signo RT1 Gel Ink Pen Ultra Fine 0.38mm Blue Black Box of 10
Uni Signo RT1 Gel Ink Pen Ultra Fine 0.38mm Blue Black Box of 10
Uni Signo RT1 Gel Ink Pen Ultra Fine 0.38mm Blue Black Box of 10
Uni Signo RT1 Gel Ink Pen Ultra Fine 0.38mm Blue Black Box of 10
Uni Signo RT1 Gel Ink Pen Ultra Fine 0.38mm Blue Black Box of 10
Uni Signo RT1 Gel Ink Pen Ultra Fine 0.38mm Blue Black Box of 10
Uniball

Uni-ball Signo RT1 UMN155-038 Retractable Gel Ink Rollerball Pen 0.38mm Blue/Black Box of 10

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

SKU: UMUMN155-038BB

UPC: 34902778142678

MPN: UMN155-038BB

Blue/Black at the Finest Published Width

Blue/black at 0.38mm is the most document-minded combination in the uni-ball Signo RT1 range, a retractable gel ink pen whose widths uni-ball publishes in its 2026 catalogue.

Two conventions meet here. Blue/black is the traditional ink for formal records because it reads as near black on the page while remaining identifiably blue, and 0.38mm is the narrowest of the three widths the catalogue lists, so a line fits where a wider one would not. Together they suit registers, forms and anything written into a ruled or boxed layout.

uni-ball states that the RT1 is retractable and publishes the ink as gel ink. The site code for this width is UMN155-038 and the group code is UMN-155, although uni-ball's own catalogue writes the same pen as UMN-155-38.

The 0.5mm blue/black and the other colours are at gel pens. The brand range sits at uni-ball, other pen types at pens, and the rest of the desk at writing supplies.

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
  • 0.38mm line width, per uni-ball's 2026 product catalogue
  • Blue/black ink at 0.38mm, the narrowest width in the published range
  • uni-ball publishes the model under the group code UMN-155, this width as UMN155-038
  • Supplied as a box of 10, all one colour
  • uni-ball describes the RT1 as an ultra fine pen for precision writing
  • Registers, logbooks and bound record books
  • Formal forms with ruled or boxed layouts
  • Correspondence where a near-black line is wanted
  • Initialling and dating dense paperwork
  • Professional notebooks and site diaries

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: UMN155-038

Mega Code: UMUMN155-038BB

Colour: Blue/Black

Line Width: 0.38mm (uni-ball's 2026 product catalogue)

Ink Type: Gel ink

Mechanism: Retractable

Pack: Box of 10

Primary Distribution Centre

Factory 5, 12 Greenway Drive
Tweed Heads South NSW 2486

ABN 18 634 002 609

Get directionsContact us

FAQs

0.38mm. uni-ball's 2026 product catalogue lists the Signo RT1 in three widths, 0.38mm, 0.5mm and 0.7mm, and UMN155-038 is the 0.38mm version.
Writing that has to fit a layout rather than fill a page. Ruled registers, boxed forms and margin notes all work better at 0.38mm than at a wider setting. If most of your writing is free-form on plain paper, the 0.5mm is the more comfortable version.
Retractable. uni-ball's product page describes the Signo RT1 as an ultra fine retractable rollerball pen, so there is no cap.
uni-ball's website writes this width as UMN155-038, and uni-ball's 2026 catalogue writes the same pen as UMN-155-38. Both refer to this 0.38mm Signo RT1.
One box of 10 uni-ball Signo RT1 UMN155-038 retractable gel ink rollerball pens, all in blue/black ink, each with a 0.38mm line.

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.